How to get things off your head in Minecraft Mo' Creatures mod

Look up at the creature and right click on it when it's on your head to remove it.

Mo'_Creatures Wiki.

Right click with a pick axe. It works for pets, litter boxes, beds, etc. I got a litter box stuck on my head...so I really had to get creative and discovered the pick axe. Works to pick Mo’Creatures items off the floor and your head!