There is no easy way to remove photos that have been glued to photo album or scrapbook pages without doing more damage. You can hire a professional conservator, but it is a time-consuming (and therefore expensive) process. Instead, leave them on the pages and scan the images to create copies that can be digitally restored using a computer.
Individual pages can be preserved by placing them in archival-quality sleeves made from inert plastic.
If you want to try to remove photos from pages, start with a photo that is dispensable. If the album is old, the animal or starch-based glue used is water soluble. Work the photo as free as you can without tearing it then apply small amounts of water to dissolve the glue. Be careful as the black dyes in paper album pages may bleed, staining the photo. In newer albums, a "white glue" may have been used, and you should apply denatured alcohol or acetone instead.