WowAce

Can we have a way to forcibly remove bad data / badly imported stuff, even if entered from other addons including this one. 

What type of bad data are you trying to clean up?  The addon has two main "buckets" of data.  I added the ability to segment data to LibAlts and Alts uses that to store the alt data from guild notes.  Every time you logon to a character in a guild it removes the current guild data and rebuilds it.  That data is always "clean" and if not you just fix guild notes (if you can, if you cannot then there isn't much to do there).

The second bucket is what you personally enter.  I assume this is what you are wanting to clean up.  If you can provide examples, I can try to figure out what to add.