I have had it with macOS.
I use a 2014 MacBook Air.
To use some apps I need, I had to upgrade to the newest macOS, but this slowed the computer down like crazy. Otherwise, I stay with an older version of OS X (Yosemite) which doesn't lag, but is not supported by many apps.
Right now I just have macOS. I want to get rid of it and use Windows & Ubuntu.
So how do I remove mac OS and dual boot Windows and Ubuntu on this thing?