Removing Gelatin Layer From Silver Gelatin Paper?
https://www.photrio.com/forum/threads/removing-gelatin-layer-from-silver-gelatin-paper.129115/
Stripping can be done by laying the RC paper in a glass dish, then pouring near boiling water on it and soaking for several minutes. You may need to dump the water and redo every couple of minutes until it peels apart. You will have some paper residue on the back, but with careful rubbing it will come off. I have done this many times with paper negatives, then mounted the emulsion on to a piece of glass.
When I worked for Kodak on color paper, I remember visiting a large commercial photo lab (about 1975) that peeled the emulsion (containing a color image) from the RC base so that the image could be put on a canvas support. They started at a corner, using a razor blade to separate the emulsion from the base, and then further separated the emulsion from the base by rolling the emulsion up on a wooden dowel. They made it look easy; I was never able to achieve the same result. Your milage may vary.
It's actually possible to physically strip the polyethylene layer from RC. If you just want to remove the gelatin emulsion, a soak in diluted household bleach will suffice.