Clean up afterwards

Yeah, I needed this too! I just forked the plugin on GitHub and added the code to do this:
https://github.com/daltonrooney/WP-OTF-Regenerate-Thumbnails

I have submitted a pull request so hopefully the original author finds this useful and incorporates it into the plugin. Until then, try my fork on GitHub and see if that does the trick.

Good job guys ?? Updating it to 0.3 now