To do this stuff I am normally browsing my music directories in PCManFM
and using the open with feature to open the files in Picard, mediainfo
or Ex Falso and it's just as easy to click the tools menu and open a
terminal window, so the method I settled in on for dealing with the
situation is....
Open a terminal window and use aacgain to undo, then get rid of the
tags, then check the tags to make sure it only shows the file names.
aacgain -u
aacgain -s d
aacgain -s c
Then use the back button in PCManFM, right click the folder with the
files and open with Ex Falso, remove the remaining replaygain tags, then
have Ex Falso recalculate the gain and save.