This is kind of a "note to self", but maybe others can find use for it too.

Q: How to view only the markdown view?
Is there some way to not get the rendered view and only to view a text mode?

A: There are two buttons at the upper right. A toggle for markdown/rendered, and another toggle for split screen. It sounds like you want no split, and markdown view. Instead of the buttons, you should be able to use CTRL+L to cycle to the view you want.