Wanted to join Beta Channel, ended up forced to upgrade to Windows 11 Insider Preview, how to stop?

So, it all started with me wanting to join the Beta Channel for Excel since I wanted to have the new features available there. So, in Excel I couldn't find the Insider Button at Account menu even though I am a MS365 Subscriber. So, I thought I had to go to Windows Settings -> Update & Security -> Windows Insider Programme to use it. After I registered there, instead of showing me in Excel Beta Channel it now is downloading and installing Windows 11 Insider Preview, what I don't want and theoretically shouldn't be able to get since my processor is too bad, it tells me that in the same window at the right side. (I am currently on Windows 10 Home 22H2-19045.3324) I have already tried to leave the program and i am getting different response to that, the Windows Insider Programme in the settings tells me that I am still set to get Insider Preview builds and the Windows Update menu also. But when I click on Leave the Insider Programme in Windows Insider Programme it directs me to a page which says This email address is not registered as a Windows Insider.... And yes it's the same E-Mail address that's linked to the program and which was connected to the page that told me the E-Mail address is not registered.

Also, Sidenote: Many buttons are not responding at all, clicking on fix the problem (see image) doesn't work, before that, changing Channels, adding E-Mail all did not work first time. And In Office clicking on Join MS365 Insider doesn't do anything either. This whole program seems verry unstable.

My questions are: 

1. How to undo all that so I don't must upgrade to Windows 11 Insider Preview

2. How to join Office Beta Channel the correct way?