Are the pages deteriorating, or likely to affect the photos? If not, then it’s a matter of convenience in viewing, and removing the photos is the issue. Start by finding out what kind of glue it is – not easy, but you can make an educated guess – rubber cement, paste, Elmers? They will all have different removal methods, and you can go from there. Remember that photographs from that period are very water sensitive and will while the emulsion will not be damaged per se, it will swell and warp if you don’t plan for treating it for that as soon as you remove the glue – generally drying between blotters and weighting them will work. If the photos are significantly older than the album, they may be made with different photographic processes.
If the pages are going bad, it’s better to remove the pages from the photos – flaking or peeling it off the back. The less you bend the photos, the better, since that will lead to later deterioration. A microspatula is good for that , you can slide it under the photo and move it side to side to free it.
Having said all that, if the only reason to remove the photos is to digitize, what about photographing the pages rather than scanning? That will give you the best of both worlds without worrying about getting out of the focal plane of your scanner.