Set File>Options>Tags>Mpeg to only read and delete ID3V1 tags.
Read the files.
Select the files.
Use the function "Delete tag" ... and wait
After the tags have been delete all files should show no tag data.
Set File>Options>Tags>Mpeg back to the normal state again, where you read, write and delete ID3V2 and read and delete ID3V1
Reread the files - they should now show the normal tag data again.