How to block websites tracking iPhone?

My girlfriend's mother has been tracking her iPhone from a website without my girlfriend's permission and is using it to stalk her position. Is there a way to stop this?

Check if there's an app called "Find iPhone" and delete it, it will disable locating your girlfriends iPhone, and her mother won't be able to track her.

Tell your girlfriend to delete the certain apps she didn't download if she doesn't know which app. Or factory reset everything and she can reinstall everything if she wants