Since Powershell v2.0 introduce the new cmdlet New-WebServiceProxy, it’s no longer needed to generate a class library to deploy/undeploy SSRS file (RDL), below are two powershell scripts Install-SSRSRDL and Uninstall-SSRSRDL that can be useful when doing an automated deployment or silent installation of rdl files to Reporting Services.

Install SSRS RDL Script:

<#
.SYNOPSIS
        Installs an RDL file to SQL Reporting Server using Web Service

.DESCRIPTION
        Installs an RDL file to SQL Reporting Server using Web Service

.NOTES
        File Name: Install-SSRSRDL.ps1
        Author: Randy Aldrich Paulo
        Prerequisite: SSRS 2008, Powershell 2.0

.PARAMETER reportName
        Name of report wherein the rdl file will be save as in Report Server.
        If this is not specified it will get the name from the file (rdl) exluding the file extension.

.PARAMETER force
        If force is specified it will create the report folder if not existing
        and overwrites the report if existing.

.EXAMPLE
        Install-SSRSRDL -webServiceUrl "http://[ServerName]/ReportServer/ReportService2005.asmx" -rdlFile "C:\Report.rdl" -force

.EXAMPLE
        Install-SSRSRDL "http://[ServerName]/ReportServer/ReportService2005.asmx" "C:\Report.rdl" -force

.EXAMPLE
        Install-SSRSRDL "http://[ServerName]/ReportServer/ReportService2005.asmx" "C:\Report.rdl" -force -reportName "MyReport"

.EXAMPLE
        Install-SSRSRDL "http://[ServerName]/ReportServer/ReportService2005.asmx" "C:\Report.rdl" -force -reportFolder "Reports" -reportName "MyReport"

#>
function Install-SSRSRDL
(
        [Parameter(Position=0,Mandatory=$true)]
        [Alias("url")]
        [string]$webServiceUrl,

        [ValidateScript({Test-Path $_})]
        [Parameter(Position=1,Mandatory=$true)]
        [Alias("rdl")]
        [string]$rdlFile,

        [Parameter(Position=2)]
        [Alias("folder")]
        [string]$reportFolder="",

        [Parameter(Position=3)]
        [Alias("name")]
        [string]$reportName="",

        [switch]$force
)
{
        $ErrorActionPreference="Stop"

        #Create Proxy
        Write-Host "[Install-SSRSRDL()] Creating Proxy, connecting to : $webServiceUrl"
        $ssrsProxy = New-WebServiceProxy -Uri $webServiceUrl -UseDefaultCredential
        $reportPath = "/"

        if($force)
        {
                #Check if folder is existing, create if not found
                try
                {
                        $ssrsProxy.CreateFolder($reportFolder, $reportPath, $null)
                        Write-Host "[Install-SSRSRDL()] Created new folder: $reportFolder"
                }
                catch [System.Web.Services.Protocols.SoapException]
                {
                        if ($_.Exception.Detail.InnerText -match "[^rsItemAlreadyExists400]")
                        {
                                Write-Host "[Install-SSRSRDL()] Folder: $reportFolder already exists."
                        }
                        else
                        {
                                $msg = "[Install-SSRSRDL()] Error creating folder: $reportFolder. Msg: '{0}'" -f $_.Exception.Detail.InnerText
                                Write-Error $msg
                        }
                }

        }

        #Set reportname if blank, default will be the filename without extension
        if($reportName -eq "") { $reportName = [System.IO.Path]::GetFileNameWithoutExtension($rdlFile);}
        Write-Host "[Install-SSRSRDL()] Report name set to: $reportName"

        try
        {
                #Get Report content in bytes
                Write-Host "[Install-SSRSRDL()] Getting file content (byte) of : $rdlFile"
                $byteArray = gc $rdlFile -encoding byte
                $msg = "[Install-SSRSRDL()] Total length: {0}" -f $byteArray.Length
                Write-Host $msg

                $reportFolder = $reportPath + $reportFolder
                Write-Host "[Install-SSRSRDL()] Uploading to: $reportFolder"

                #Call Proxy to upload report
                $warnings = $ssrsProxy.CreateReport($reportName,$reportFolder,$force,$byteArray,$null)
                if($warnings.Length -eq $null) { Write-Host "[Install-SSRSRDL()] Upload Success." }
                else { $warnings | % { Write-Warning "[Install-SSRSRDL()] Warning: $_" }}
        }
        catch [System.IO.IOException]
        {
                $msg = "[Install-SSRSRDL()] Error while reading rdl file : '{0}', Message: '{1}'" -f $rdlFile, $_.Exception.Message
                Write-Error msg
        }
        catch [System.Web.Services.Protocols.SoapException]
        {
                $msg = "[Install-SSRSRDL()] Error while uploading rdl file : '{0}', Message: '{1}'" -f $rdlFile, $_.Exception.Detail.InnerText
                Write-Error $msg
        }

}

Uninstall SSRS RDL Script:

<#
.SYNOPSIS
        Uninstalls an RDL file from SQL Reporting Server using Web Service

.DESCRIPTION
        Uninstalls an RDL file from SQL Reporting Server using Web Service

.NOTES
        File Name: Uninstall-SSRSRDL.ps1
        Author: Randy Aldrich Paulo
        Prerequisite: SSRS 2008, Powershell 2.0

.EXAMPLE
        Uninstall-SSRSRDL -webServiceUrl "http://[ServerName]/ReportServer/ReportService2005.asmx" -path "MyReport"

.EXAMPLE
        Uninstall-SSRSRDL -webServiceUrl "http://[ServerName]/ReportServer/ReportService2005.asmx" -path "Reports/Report1"

#>
function Uninstall-SSRSRDL
(
        [Parameter(Position=0,Mandatory=$true)]
        [Alias("url")]
        [string]$webServiceUrl,

        [Parameter(Position=1,Mandatory=$true)]
        [Alias("path")]
        [string]$reportPath
)

{
        #Create Proxy
        Write-Host "[Uninstall-SSRSRDL()] Creating Proxy, connecting to : $webServiceUrl"
        $ssrsProxy = New-WebServiceProxy -Uri $webServiceUrl -UseDefaultCredential

        #Set Report Folder
        if(!$reportPath.StartsWith("/")) { $reportPath = "/" + $reportPath }

        try
        {

                Write-Host "[Uninstall-SSRSRDL()] Deleting: $reportPath"
                #Call Proxy to upload report
                $ssrsProxy.DeleteItem($reportPath)
                Write-Host "[Uninstall-SSRSRDL()] Delete Success."
        }
        catch [System.Web.Services.Protocols.SoapException]
        {
                $msg = "[Uninstall-SSRSRDL()] Error while deleting report : '{0}', Message: '{1}'" -f $reportPath, $_.Exception.Detail.InnerText
                Write-Error $msg
        }

}

Install-SSRSRDL Powershell Script
Uninstall-SSRSRDL Powershell Script

For permission check this blog: https://randypaulo.wordpress.com/2012/02/22/powershell-set-user-permission-in-ssrs-item-sql-reporting-server-using-powershell/