Wet gauze. Wet gauze does it best.. And the lesson is to use as little adhesive as necessary.
Wash cloth. Use a damp soft wash cloth to remove the adhesive then rinse the ash cloth out.
Difficult. This is tough to do. Many use their fingers and nails. This could be painful and you might scratch yourself. A gauze pad works well as does a q-tip. Best not to use much, or use the powder. If you have to use the adhesive daily, your dentures do not fir properly, or you are using them to do things that they are not intended to do and you are harming your underlying bone. See your prosthodontist.
Adhesive removal. Can be hard and tedious . They purposely make it that way. Try a wet wash cloth or a gauze.