the non-manual approach is to speed the clip up, and turn frame blending OFF.
then FCP wil simply drop frames
speeding up to 110% would remove every 10th frame (although i haven't really done the figures)
my guess is it would be a bit hit and miss, not entirely accurate.
it;s possible t do it manually, but not frame-by frame
lets say you wanted to very accuraltey remove every tenth frame.
on a track above your clip place 9 frames of slug, et 1 frame of text
copy that and paste at the end of itself
then copy those 2 instances and do the same, and keep doing this till you've covered the entire clip (wont take long).
now do a search for "slug". you may have to use the find between in and out points function
find all, an delete all the slugs
select all the 1 frame text left over
hold shift and drag them down over the clip, overwriting every tenth frame, then delete
now take whats left of the clip, drag into the canvas, and all those bits will be edited back into the timeline.