The low level crafting materials are generally not used once you've reached max level, in both crafting and CP150 on your account, so you could sell in a guild store, vendor them to an NPC, or just get rid of them.
Mine will just sit in my craft bag for eternity, since they aren't worth much.
I just let them sit in the craft bag in case I need to make myself some training gear in the event they add more character slots or if I need to make someone else training gear or low level PVP gear.