Did you suddenly find no more space on your mac? Did you discover that .MobileBackup is taking a lot of space?
I usually use an external drive to backup, but when not available Time Machine create an internal backup!
The easy way to get your space back is to delete what inside .MobileBackup and then disable the service.
sudo tmutil disablelocal
And if you want to renable it
sudo tmutil enablelocal
Don’t forget to reboot your mac, yes true, you need to reboot.