How do we determine whether it is 'your shit' and not someone else's? Do you have a right to erase my past if it intersects with yours? Would you have the rig

How do we determine whether it is 'your shit' and not someone else's? Do you have a right to erase my past if it intersects with yours? Would you have the right to erase memories from my brain if they referenced your past? Where is the line?