You should only strip your cables if you have the correct equipment to do so.
For the most part, the copper content inside your PVC pyro is what makes it so valuable. Scrap Local recommends that you strip the insulation from your cables, extract the copper inside them, and sell this metal waste separately.
However, cable stripping is a time-consuming and messy process which can damage the copper content inside your wires if it's not carried out with care.
Use a professional cable stripper to retrieve the copper from your PVC pryo safely. If you don't have this tool, then leave and scrap your cables as they are.