Create a separate account for them, and make sure you have FileVault turned on so your home folder is encrypted.
I've managed to get this concept across to authorised repairers who don't speak english (and I don't speak Thai).
I've managed to get this concept across to authorised repairers who don't speak english (and I don't speak Thai).
FileVault 2 encrypts your entire boot volume, so there's no separate encryption of your home folder going on. If you give someone any of the passwords that unlock the boot volume, they could get all of the data off it (by using target disk mode or booting to single user mode, etc.)
Having said that, prior to my recent visit (failing mbp fan) my trips had always been for failing/failed discrete graphics (about 5 trips on 2 different generations of 17" mbp) so a reinstall is inevitable because making macOS work properly after a mainboard replacemnt is more work than reinstalling from scratch
- Boot into single user mode...
# mount -uw /
# rm /var/db/.AppleSetupDone
# reboot
Reboot the machine and it walks you through a re-run of setting up the OS X set up assistant, which allows creation of an admin account.