Wipe the frame down with 91% alcohol. The wipe down the regions where the lead tape is sticking to the frame with mineral spirit. You can use a razor to lift an edge or corner of the lead tape. Once the mineral spirits can reach the adhesive, it will start to dissolve the adhesive. Take your time and do this in a ventilated area.
Or you can leave the mess alone and just tell your friend to remove the mess. "That will teach them start taking care of their equipment!"

Guess this is better than receiving a frame with mold growing on the overgrip.