If what you're trying to remove from the background is complicated and fiddly, the best tool for the job would probably be the
Extract filter. It's a bit too much to describe in detail here, but you can look it up in Photoshop Help, or try out an online tutorial:
photoshop extract tutorials - Google Search
If the difference in tone/colour between your subject and the background is quite distinct, you might also get good results by using the
Background Eraser tool. Again, its usage is explained in the Help file.