If the permissions are set in public folder , air drop , shared folders , home folder , they should be disabled & be set as custom access .
In system preferences > date & time , location services should be enabled .
Shut down the system & plug the charger press command + R key + power button > when a sound comes release the power key but keep on holding command & R key until grey screen appears .
Click on utility on top menu bar & choose terminal . Type resetpassword & hit enter . close the terminal window , now enter two times username password in the field .
Click on save , restart from apple logo its done .
Now open system preferences > iCloud > enter apple id & password follow the upcoming steps it will ask for four digit iCloud code that is constant , enter it an SMS Will come on your mobile , enter the code the system will be configured with i cloud id .