How to turn off SIP?

All of the articles I have found on the web seem to refer to more recent MacBooks. How do I turn off SIP on a MacBook Pro Mid-2012 model running Mojave? All that command-R stuff I have read only forces me into a MacOS Utilities window with 4 useless options.

Also, why was I unable to log into this forum using my username and instead had to use an Apple ID and was forced to created a new username? I now have two previous usernames that are useless: cupboy and cupboy1. I am now cupboy2 but I guess when I login again I will need to create a cupboy3? What's up with this?