Check out Heath Stewart's post: The Patch Cache and Freeing Space. Heath describes the purpose of the $PatchCache$ folder as it applies to Visual
Studio and any other updates that use a .msp file.
You can delete it (well, the specific folders for the updates you've applied), however by doing so you remove the ability for Windows to retrieve media it needs when applying future updates. In otherwords (though it probably won't affect SharePoint) you
may require your original media to apply updates slike a Service Pack. This used to be pretty common with the Office Suite of products -- to install a service pack it would ask you to insert the original CD or floppy disks.
The recommendation is to keep the folder if you have the space. If you don't have the space (your system drive should be a minimum of 80 GB), then deleting is an option.
If deleting system folders isn't your idea of a good time, as an alternative you can use the Disk Clean Up Wizard to purge these files for you. Check out Scott Hanselman's
Guide to Freeing up Disk Space under Windows 7 which applies to Windows Server 2008 R2 and Windows Server 2012.
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