Removing cardboard mount from 1920s photo to see back of photo

[pinot]

Hoping for the voice (or hand) of experience to help with the above; the photo, professional, monochrome, about 1920, is of a large group amidst which some of my relatives may be. My hope is that there may be some information on the back of the photo, but I don't want to risk damage without advice. The cardboard mount is soft, not very thick, and of a fairly coarse weave. Feel sure that someone has done this successfully; any advice gratefully received.  (Enjoying my first hat)