Is it still possible to use rich text with css for styling
No, that doesn’t work any more, other than inline styling with HTML.
CSS is now applied via Settings->Appearance->Custom CSS.
Is it possible to hide the glide top bar using the css
Quite possibly. If you watch the video in the doc that I linked to, it shows you how to target components with CSS and apply it. So it should be just a matter of identifying the correct class, and then applying appropriate CSS.