When you need to remove a SharkBite push to connect plumbing fitting you use the SharkBite removal tool that you can buy at the hardware store near the SharkBite fittings.
The SharkBite removal tool is usually an orange colored tool that kind of looks like a horseshoe and you put the Sharkbite removal tool onto the Sharkbite fitting and push it backwards into the fitting where it connects to the pipe.
As you pull back on the SharkBite fitting with the tool the SharkBite fitting should come apart and if not you need to push harder and sometime twist the SharkBite fitting back and forth.
Some of the SharkBite fittings can be hard to remove but usually they come apart pretty easily.