@karolistom34493 try to uninstall the APP:
Open the Family Link app
# Tap Menu in the top left
# Tap Manage family
# Select Delete family group
# Enter your password
# Tap Delete
If that does not work you may have to do a factory reset. Now, with that you will lose all of you pictures, music, SMS, contacts etc. Make sure that you back all of this up beforehand. Also, you will need the username and password for the email you've used to setup the phone in the beginning.