Is there a way to drop some diagrams?
Some are completely useless for me..
There's an option to drop items from the inventory screen. Selling them would be a better option, though, if you're sure you don't want to keep them.
... Actually, do you mean the stuff that's listed on the crafting screen? I'm not sure if you can get rid of any "unwanted" items, once you've discovered them. I could be wrong, but is there an option to temporarily hide items from the list... ?