Is my mac being hacked by a user called Guatoan? And how can I remove this user?
It’s not clear what user ID you are running - so to rule that out - what does this command show?

id


Next, you’ll want to inventory your backups to know if you can erase everything and or need to make a backup. Next you can inventory all the accounts - run this command

dscacheutil -q user | grep -A 3 -B 2 -e uid:\ 5'[0-9][0-9]'


This will fetch all the users with their respective directories.

Then you can delete the user using this. sudo is needed as the commands need to run as root.

sudo dscl . delete /Users/your user name(name from the output)
sudo rm -rf (dir from the output)


Only delete the dir if it is not one of the system ones - probably only do that if it is of for /Users/X where X is not one of your normal users.