In Ubuntu 17.04 there was 'Rotation' menu in Display tab. But now in new version of Ubuntu, there's still a Display tab but no more rotation menu. Now I can't turn that off again since I upgraded to 18.04 LTS.
Ubuntu – How to turn off screen rotation in Ubuntu 18.04 LTS
18.04display-rotationgnome-shellscreen
Best Answer
The best solution I have found so far is to use the icon that is available in the top right corner of the screen, when you click on the down arrow. The icon is the one in red in the screenshot below:
It might also look like this: