When your WSUS folder starts getting out of control, or you've removed a lot of stuff and the cleanup isn't giving you back your space, here's how to do a reset.
How to Do a Reset:
Note: You may want to execute the procedure below during off hours as your WSUS server will be downloading quite a bit of data.
1) Correct any settings above or disapprove any unneeded updates.
2) Close any open WSUS consoles.
3) Go to Administrative Tools – Services and STOP the Update Services service.
4) In Windows Explorer browse to the WSUSContent folder (typically D:\WSUS\WSUSContent or C:\WSUS\WSUSContent)
5) Delete ALL the files and folders in the WSUSContent folder.
6) Go to Administrative Tools – Services and START the Update Services service.
7) Open a command prompt and navigate to the folder: C:\Program Files\Update Services\Tools.
8) Run the command WSUSUtil.exe RESET
-This command tells WSUS to check each update in the database, and verify that the content is present in the WSUSContent folder. As it finds that the content is not present in the folder, it executes a BITS job to download the content from Microsoft. This process takes quite a bit of time and runs in the background.
How do you tell when the process is complete?
Other than noticing that the WSUSContent folder is no longer growing you can also check the SoftwareDistribution.log:
C:\Program Files\Update Services\LogFiles\SoftwareDistribution.log
When you start the reset process, you should see a line towards the bottom of the log which looks like this:
WsusService.13 ExecutionContext.runTryCode State Machine Reset Agent Starting
After waiting for some time, check the log again and search for the text “State Machine Reset Agent Finished”
WsusService.13 ExecutionContext.runTryCode State Machine Reset Agent Finished
http://blogs.technet.com/b/gborger/archive/2009/02/27/what-to-do-when-your-wsuscontent-folder-grows-too-large.aspx