Accidentally in the wrong version of TurboTax, how do I get back to the normal version?

If you have any self-employment income or a T4A with income in box 28 in the wrong place, it will upgrade you automatically.  Standard version does not do the same things it did last year.

I don't have self-employment income or a T4A with income in box 28, I just clicked a wrong button and need to get back to the standard version.

That could be a problem.  From what I have seen on here, if you start a new return, it wants to start a new version of what you have got.  You can start a new return under a new sign in, or try to start a different version to see if it will cooperate.