No admin account in macOS I know this has been answered before with the whole "rm /var/db/.AppleSetupDone" thing in High Sierra but when I try to do this, I'm told that it's a "read only file system". Is this because I have my SSD encrypted? 

Whatever the case, I'd really appreciate a work around.
When launching single-user mode, you're informed with the following text that you need to mount the disk as writable before you can make changes.


Root device is mounted read only

If you want to make modifications to files:
        /sbin/fsck -fy
        /sbin/mount -uw /



This text is printed when you launch single-user mode. Do as it says to mount with write access.