Safe Boot is your magical way to have the computer delete purgeable and temporary files, like boot caches. Hold shift down and once it gets to the login window,

Safe Boot is your magical way to have the computer delete purgeable and temporary files, like boot caches. Hold shift down and once it gets to the login window, restart again. Otherwise, go to Recovery mode, mount the disk in Disk Utility, and then open Terminal and rm some shit.