I need to downgrade from Mojave to High Sierra but am not sure if I can safely erase the HDD in order to install the new OS.
I'm aware that I can create an installer on a USB drive for High Sierra or I can reinstall the version of Mac OS that the machine came with using Internet Recovery mode. Regardless, I know that I'll need to erase the HDD. I was about to do so but it gave a warning message that erasing the HDD will also erase partition disk0s2 and I'm not sure what that partition is for.
After downgrading to HS, I will move over files that I need from the a time machine backup I created on Mojave. I’m aware that I can’t install the whole backup from time machine as the backup was taken on Mojave.
Any help will be much appreciated. Thanks.