I'm running Windows 7 as 64 bit and followed the instructions from crazycheese (tx for the thought) he tried in Linux.
Result: when restarting firefox the uBlock Origin xpi file got removed ... including a savecopy I created (just renamed the original file to *.old).
Interesting enough, the deleted files are not in the system trash. A new installation is not possible. For more, uBlock origin is also not appearing any longer in the add on list. Means to me that it got removed.
Hence please be careful when following the steps under windows ...