I have a Monoprice MP10 with magnetic flexible paper coated build plate and I have just tried printing bed level test which is, of necessity, very thin on the build plate.
Watching the item print, I saw that the bed level was obviously way way off at the back left corner and down the left side. I was printing with PLA. There was no point in letting the print continue so I stopped it, let the build plate cool down and tried to remove the print.
The bottom line and right hand side came off cleanly but the top left corner and all down the left side stuck firmly. As it was so thin a layer there is no chance of getting something underneath an edge without damaging the paper surface. I tried acetone but this had no effect other than turning the surface white and thin cracks appearing in the paper surface. Wiped down with alcohol which toned down the white but was no help in getting the thin layer of PLA off.
I tried reheating surface, no joy. Does anyone have a foolproof way of getting this off as soap and water don't work either?