Check with the manufacture if possible. Modelhaus works with Bleach White, Drag City recommends Dawn dish soap. Jimmy Flintstone uses mold release from hell soak overnight in bleach white, wash with soap and water, dry wipe with lacquer thinner wash in soap and water then wet sand the surface. Generally overnight in Bleach White works with most resin.
Hot tap water and then a dip in cold water while holding the part should work fine. Might take more than one try to get it right.