Acetone(nail varnish remover)make sure it's pure with no additives.
Acetone(nail varnish remover)make sure it's pure with no additives.
As it's hardened do no use heat , Acetone or MEK will soften it enough for you to wipe it off , Nail varnish remover normaly is Acetone with something like Lanolin added , Use that as it is the solvent acting on softening the residual glue so you can wipe it off , wrap it in paper towel's and drizzle the solvent on to the towels and leave for 10 min and then wipe off.
Depends a bit on what the composition of the adhesive is. Acetone, MEK are worth trying, iso propanol might be worth trying too. I've had success with white spirit & also that very popular spray lubricant **40. As has been said try to leave it on to soften, the paper towel trick works well but some solvents evaporate very quickly, especially in the warm weather, watch out for fumes/ flammability, avoid the vapours & be aware of the H& S issues, some are nasty chemicals......
In order of potential hazard. Try WD40 first, then paraffin then petrol and then cellulose thinners or acetone or MEK. One of those should shift it.