SOLVED: Is It Safe To Delete The Old Exchange Builds In C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa\prem ?

In a word, yes. You can safely recover many GB’s of disk space by deleting the old versions of C:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\Owa\prem , however there are a couple of things to know before you go deleting what you think are old and unsused MS Exchange files / folders.

How To Safely Remove Old Exchange OWA Files and Free Up Disk Space

In the example below we had about 26GB of space consumed on a 100GB drive, which was not good:

Because it is possible that you are using more than just the most recent build, you should run a simple PowerShell command to find out what version(s) are in use:

1 – Launch the Exchange Management Shell as an Administrator

2 – Copy / Paste these two commands to figure out which version of OWA is in use

$ExchangeServers = Get-ExchangeServer | Sort-Object Name
 
ForEach ($Server in $ExchangeServers) { 
    Invoke-Command -ComputerName $Server.Name -ScriptBlock { Get-Command Exsetup.exe | ForEach-Object { $_.FileversionInfo } } 
}

Even though we know that only the active version is what counts, we still kept the last 3 versions, just because we are paranoid. We were able to delete about ten 2GB OWA folders and recover 20GB of disk space which made our client very happy.