Playing primarily a mage for the first time, although I'm finding being 100% mage does not work for me. Anyway, as I get higher in level (currently lev 11) I buy better spells. Is there any reason to use a lower level spell? For instance, once I have Stoneflesh, why would I ever use Oakflesh. Same thing with Flames and Firebolt, just to name a couple. If there's no valid reason, is there any way to delete spells from the spellbook so as to free up some screen clutter?

In the case of Oakflesh and Stoneflesh, I still use OF if I'm a low level. It's more magicka friendly than SF.