Maybe rubber cement?
You should scrape the old glue off if you expect a flat surface.
First, just try to peal it off. If that does not work, use a wet sponge to soak the material. It should loosen the glue, then peal. If that does not work, they make special solvents. You score the wall paper then mist the product on.
soak it in water then peal it off.
There is no metal that starts off as glue.
Meat is skinned when it is an animal we eat
Depends on the kind of glue - "Name your glue"
Depends what kind of glue.
you have to put more glue on it, it will glue itself to the old glue, and be easier to remove
Try Goof Off, it softens Super glue so you can pick it off.
It is a version of PVC glue.
Turn the glue gun on to loosen the glue, then, if the glue is persistent, use a wooden stick to CAREFULLY pick the glue off.
Depends on the type of glue, but most will come off with Goof -Off or Goo-Gone.