TTYs exist and operate in Mac OS X and macOS just as they do in any other UNIX or UNIX-like operating system. When macOS boots, the TTY that inits to subsequently load the GUI is always console. Subsequent TTYs opened from Terminal.app or other emulators are listed from ttys000 and the digits increment one at a time.
You can open Terminal and check your TTY ...
Just perform an erase install. Boot to macOS recovery and then repartition the whole drive and the installer downloads from the internet.
How to completely reinstall Mac OS X?
My answer here works best if you use internet recovery so you don’t need to mess with making a bootable usb and then get to recovery.
I read your this article. Follow the steps outlined in the article with these adjustments. I'd set up three partitions instead of four: macOS, swap and Windows. I'd adjust the macOS partition to the size you want to for linux. I'd install linux over the top of the macOS partition.
I've set up a triple boot system before but I haven't tried this procedure. ...
You might want to make sure Atom app is actually executing from the Applications folder and then install the Shell Commands utility.
I was executing Atom from my Downloads folder and every time I rebooted the atom commands weren't recognized.