It’s been really frustrating just trying to remove this thing from my project. Is there a way to do it? Everytime I delete the files it just reinstalls itself.
Huh?
There is nothing that reinstalls the project if you delete it.
Just deleting the Assets/AstarPathfindingProject folder should be enough. Could possibly be Unity that tries to recreate some meta files, but in that case just make sure Unity is closed before you delete it (but that really should not be required).