loosening 1/2" threaded pipe in wall

I have a tiny drip behind my wall that I'd appreciate some advice on.

My 4" 1/2" satin nickel nipple wasn't long enough so I added a coupling and "close" nipple with two wraps of teflon thread (the right direction).

In order to get the shutoff aiming the right direction AND tight, I'm afraid I might've gone too far.

If it unscrews from either side of the coupling behind the wall, how do I get that out if I've only got a 1 1/2" hole? Is there some 'thingy' that I can screw in the wrong direction and loosen it enough to start all over.

If I'm that tight, might I have any luck just backing it one rotation without having to get the coupling and close nipple out of the brass fitting in the wall?

Very slow drip, I think...seeping through grout in corner...any chance it'll just stop on it's own?

Thanks for any time you spend reading and or writing...near the end on this bath...no back left...little patience...but do see the light...you've helped me before greatly here...hoping I've not got a headache!

Cordially,

Doug in NJ

You need an internal nipple wrench... check at your local plumbing supply house.

Two wraps may not be enough, especially if the threads are rough or not up to specs.