Hi there,
i tried to delete unnecessary ID3.v2 tags as usual and also lost my .v1-tags. May that be a bug?
Regards,
Flo 
Removing ID3v2 Tags via File, Remove Tag or [Ctrl+R] works fine for me and leaves the ID3v1 Tag according to the settings at Options, Tag, Mpeg, Remove.
Please check your settings again and please provide a step by step description if you're still thinking that there is a bug in Mp3tag which needs fixing.
Best regards,
~ Florian
I've checked again and I've realised that the problem is not about the actual removing but about the shown size of the tag. It simply shows 0 afterwards!
ID3v1 tag size should be displayed again with the latest development build. Can you confirm this?
Thanks for reporting!
~ Florian
Affirmative 