I use the taglib sharp library to remove all tags from my songs with the command
Track = TagLib.File.Create("C:\test\Super Trouper.mp3")
Unfortunately, TagLib# doesn't support Lyrics3 tags. In an MP3 file, TagLib# will detect and can remove only APE, Id3v1, and Id3v2 tags.
After saving the file with tags removed by TagLib#, you could do something like the following with your own code:
LYRICSEND. If not, close the file.
LYRICSBEGIN. If so, truncate the file at that point.
This is not the most efficient strategy but I'm imagining the number of files with these tags is quite low so most should stop after step 2.