The EFI will not take up space on your primary partition. It could be snapshots that are taking up space or hibernation file. See here on how to delete snapshots: https://www.macworld.com/article/3260635/macs/how-to-delete-time-machine-snapshots-on-your-mac.html To disable Hibernate: Resource: [Guide] Native Power Management for Laptops | tonymacx86.com *Direct quote from above guide: "Be aware that hibernation (suspend to disk or S4 sleep) is not supported on hackintosh. You should disable it: Code: sudo pmset -a hibernatemode 0 sudo rm /var/vm/sleepimage sudo mkdir /var/vm/sleepimage Always check your hibernatemode after updates and disable it. System updates tend to re-enable it, although the trick above (making sleepimage a directory) tends to help. And it may be a good idea to disable the other hibernation related options:" Code: sudo pmset -a standby 0 sudo pmset -a autopoweroff 0 If these don't clear up your disk space then it has to be some app/setting that you are using. Don't know why you can't erase an SSD.