It is not removable (if you have a per-plans built airplane). However, you should be able to chop the stick in half.. close to the base -- far enough up the stick where you'd have access to it.. and perhaps far enough up where it clears the fabric boot..
Then use a smaller diameter (or larger I guess would work too) steel tube to rejoin the two sections of 'stick'. Use two AN3 bolts to secure the two halves of the stick. Maybe one side can use a bolt with cotter pin for easy removal.
The legacy RV12 has only the PTT button in the stick.. which you could probably just disconnect permanently.. or relocate elsewhere. The real complication is that the stick is curved. not just a straight pipe like the old RV-6/7 was.
And as you know, this is one of the few airplanes that you enter from the front of the wing.. which may be more difficult (or maybe less) for your wife.. So I'd recommend that you compare entry/exit the RV-12 against a more traditional entry/exit plane (rv6/7/9/10/14). If the 12 is the best for you.. then issues with the stick can be worked out. If you're already dead set on the -12, you can purchase an extra stick from Van's, and start modifying it now.