Wallpaper paste is necessary to adhere wallpaper to a wall or surface. Once you have applied new wallpaper, you may notice excess paste. The wallpaper paste must be removed gently or you will end up tearing the wallpaper you just put up. There are a few ways you can try to remove wallpaper paste without destroying what is underneath it.
Turn on a blow dryer to a low heat setting.
Point the blow dryer at the wallpaper paste to try and melt the glue.
Pour 1 cup water into a bowl.
Add 1/2 tsp liquid dish soap to the water.
Dip a sponge into the liquid, and squeeze out the excess water.
Gently rub the sponge onto the excess wallpaper paste until it comes off.
Dry the area with a cloth.