i fitted a stem mount to fit a tomtom rider a few years ago, i'm now trying to fit a QUAD LOCK motor cycle fork stem mount to use my iPhone xs max,rather than the tomtom, how on earth do i remove the existing stem mount.i've tried a couple of time's in the past & it's a right pain.i simply can't pull it out, is there a method.....
Slacken it off and tap it to release the cone which is expanding the tube in the stem.
There may be some help here tapps, I know you fitted it yourself but this vid might be of use ..good luck
https://www.youtube.com/watch?v=nL-Ahy83RJ0