If your wallpaper won’t easily strip from the wall, you have a couple options. Dissolving the glue and removing the wallpaper is the most obvious choice.
You might be able to do this with water. Turn off circuits which reach outlets or switches on the wall in question and wet down the paper by applying warm water with a paint brush or sponge. Or spray it on the wall with a pump sprayer. Let it soak for at least 15 minutes, and see if you can strip it off with your fingernail. If it’s not ready, apply more water. Scoring the wallpaper in a diamond pattern will help get the water right into the glue, but try not to score the drywall or plaster underneath.
When it’s ready, use a drywall knife or wallpaper scraper to remove the paper.
To make a tougher remover, mix an equal amount of white vinegar in with the water.
Or explore chemical removers. Make sure you follow all instructions and wear protective clothing.
And a steamer, which you can rent, really does the trick, particularly if you have to remove a number of layers. Concentrate on a small section at a time, and lift the wallpaper away as you steam. Scoring helps.
When it’s all off, remove the remaining glue using the technique we described last time.
The alternative is to paint over the paper. Maybe the paper’s holding in chunks of plaster, and you don’t want to get into that kind of repair. Skim-coat the seams with drywall mud. If this lifts the paper, don’t pull it off; as it dries the paper will sink back into place. Lightly sand the compound, then paint with a cheap alkyd primer and topcoat with alkyd or latex.