Don't let it worry you. It's only electrons...
I first went through this problem when I had paper books and only had so much space to store books in. I would cull the paper books and sell them used. I don't get too many freebie books, but I have around 1400 books on my library. There's around 100 more titles I would like to add, if I could buy decent e-book versions.
We were reared to believe that books were the finest flower of civilization (true), and that they were scarce. They aren't scarce any more. So don't worry about deleting those you don't want, either somebody else will save them (for whatever reason), or they weren't worth saving.
RSE (Cabell fan)