Mix vinegar into water at a ratio of 1 part vinegar to 4 parts water. I am in the process of removing the backing now from our 20 year old wallpaper. First time I have ever done it. The wallpaper came off easily with this solution, in some spots the backing came with it, in other areas it didn't. I am using a plastic spatula to gently scrape the backing paper off the drywall. We were told by a lady at Lowes who had hung wallpaper as a job for years that you can put new border over old (and I am assuming just over the paper backing if you get one that is thick and textured that it won't show through. We will be trying that in our breakfast area where we just had border. Again the paper came off easily but the backing won't budge. My new border is wider and thicker so we think we will be okay. Hope yours turns out okay.

I'd suggest trying a steamer to remove the wallpaper which was not mentioned in the link provided by christophern. We've found that to be the best method. It is a pain in the butt no matter how you do the job but it is way better to remove the old paper rather than doubling your future troubles. Wagner makes a wallpaper steamer and sells it for about $40.

I like pursuing Schumacher's IG for ideas. https://www.instagram.com/schumacher1889/?hl=en

If I don’t wish to remove the current multiple layers of wallpaper on my plaster walls would using paintable wallpaper over them make it any easier to remove later than simply painting over them? There are parts of the old paper that would need repaired before we could do either. If you want to know the why to this question read on, its long, but I have very strong feelings about why I don’t wish to try to remove this paper. The full situation: We’ve been slowly remodeling our early 20th century house. Most of the walls are plaster except for the back half of our upstairs which was added later and is wood paneling. Every inch of the house is covered in wallpaper. The original plan was to eventually drywall the paneled rooms upstairs and to remove the wallpaper to the original plaster downstairs. Re-doing walls however is much further down our current to-do list so in the interim I’ve painted over the wallpapered-paneled bedroom walls. I’ve learned from this that if the wall and paper is in good shape you can barely tell there is even wallpaper under it, but if they are not every imperfection will show. Here is the before and after of my daughter’s room. Even knowing it’s painted wallpapered I always have to look very hard to find the seams. In our bedroom however I see the creases in the paper the minute I walk in (it’s still a 1000x better than the old wallpaper was!) I have also now experienced removing wallpaper from old plaster walls and I don’t wish to go through it again. We removed the wallpaper from my son’s bedroom in the old part of the house. The paper removal was itself was fine, but the walls were in terrible condition and covered in lead paint. Dealing with these issues took about 10 weeks. Those walls are beautiful now, but I am in no hurry to repeat the disruption and stress this caused. I am now considering what I want to do with the walls in our main living space downstairs. These have many, many layers of wallpaper on them. We saw evidence of this when taking down some crown trim and from some “helpful” wallpaper removal by our 6 month old pup. We’ve been dealing with the wallpaper, most of which, while dated is at least somewhat neutral in tone. However, we are talking about removing a fake beam in order to be able to place our TV on that wall and the current wallpaper only goes up to it. My husband has talked of putting drywall over the plaster. This not only seems weird to me but problematic in that much of our original trim would likely be damaged in the effort and we would never be able to match it exactly. At this point I feel like our best option would be either to paint the current wallpaper, or to put paintable wallpaper over it and paint that. Would it likely be easier to remove paintable wallpaper in order to restore the walls at some point if that is what is wanted or would it equally hard? I’m almost considering this more for someone who comes after us because frankly the only way I foresee us re-doing these walls the “correct” way would be if we had enough money after my children grow up and leave home to have a professional come in and do them all at once. Honestly, that seems unlikely to me, we’re older, with young kids trying to save for retirement, and college and remodel this house. We’ll be lucky to have enough for retirement and I don’t know that I’d want to stay in such a large house when the children are gone anyway. I know nothing about hanging wallpaper, but I do know how to paint it, so I think that would “easier” for me, and I also can’t imagine texture on every wall, I’d really have to find something super subtle. Anyway, I’m simply not up for removing the paper and dealing with what’s underneath, so what’s the next best thing?