Hello,
I have a very effektive methode, but I don´t know how to describe it, but I try:
Search for a point/place, were the rubber is mostly loose. Sting carefuly between the rubber and the rim a long, round thing like a screw-driver (I always use a hudy 2,5mm hex driver, as longer, as better) .
If the tip of the screw driver looks out the other side of the glued tire, begind to turn it carefuly in left and right direction while you hold/fix the side with hex tip with your other hand.
What I mean: Hold the tip and press it in the direction you built up the pressure while you turn the screw-driver left and right.
(You will feel the effect)
In this way you can release all rubbers from the rim AND to 90% you can use the released rubber for any other application!
Hope you understand what I mean...
If not, please send me a PM with your @, and I will send you a video!