What is the best way to remove wallpaper from a painted wall?

fabric softener and water in a spray bottle works well, also smells nice.. most wallpaper have a top layer try and peel some of that off so you can spray the adhesive layer..

You will need to score the paper since it is painted. What I use is hot water and vinegar in a spray bottle and a foam roller. Saturate the paper, let it sit for a while and check every so often if the paper starts to peel off.

https://www.familyhandyman.com/walls/the-best-way-to-remove-wallpaper/view-all/

You can also rent a wallpaper steamer to use and this will help loosen wallpaper glue. Get a flexible metal scraper or a plastic putty blade and carefully remove moistened wallpaper. Take your time. It is very easy to tear up your sheetrock if the wallpaper is being stubborn or gouge a hole in your sheetrock.