How can I make an untameable entity follow the player with a GUI?

I'm making a mod with NPCs that you can interact with them in a GUI, and I want to put a button that when you press it the NPC follows you and if you press another button then it doesn't do that anymore and goes wherever it wants, but I don't know very well how to do it, I've looked for tutorials and they all only say if I make it tameable, but I don't want to make it tameable, what can I do? I'm new to MCreator and I really like it but it's a bit difficult for me to handle and I don't know very well how to program it ;-;