Evict it with unlocker (X86 / 32bit only):http://www.filehippo.com/download_unlocker/
The unlocker option will appear in your right click context menu.
Did the squatter bring in nasty friends? The folder didn't contain a crack or modified .exe for a paid for application?
If so you may want to run a free antimalware app such as Malwarebytes' Anti-Malware:http://www.malwarebytes.org/mbam.php
just to be sure there is nothing lurking there that shouldn't be.