Applying a REM pose should remove the actual morph deltas so that the morph does not work any more, but I don't think it removes the keyframes for that channel. You need to delete either the whole targetGeom channel, or just the keyfremes from it, deleting the whole channel is probably easier. The keyframes are contained in the "keys" section of the channel.

I'm not sure why you can't find the morph names in the text editor. What are you trying to edit, a pz3 or a cr2? Do you have "Use external binary morph targets" enabled in your General Preferences?