The Tavern

With only 52 inventory slots in the game and possibly dozens of books, is there any way to discard or store unneeded spell books?

Yes, in trunk the player has a spell library.

thanks for responding. Its too bad my current campaign is in .21.

You can drop items with the 'd' key.

And, correlated - you can search for items with cntl-F. So say you find the spellbook with Shatter, Ignition, Glaciate in it, on D:2 - drop it, and if you decide you want one of those spells later, you can just search for it, and fast travel there.