I have a 1950 home with pink plastic tiles on the bathroom walls. The walls are some sort of plaster. These tiles have to go. They pry off easy enough, but there is some sort of adhesive left behind. Any ideas on what it is?

The tiles have "Meets FHA specifications Made of STYRON A Dow Plastic Rib-lock" in raised lettering on the backside.

Is there a safe way to get this stuff down without gouging up the walls more than I already have? Also, when I remove some of the tiles, there is an odor. Smells like a musty tent. Any suggestions? Eventually I will be repairing/replacing the walls, but 12 years with the silver wall paper and pink tiles is too much.