How can I exit the Apple Beta Program?

Hi there!

I inadvertently used Apples "Feedback Assistant" to report a bug in HomePod Software 18.2 and now on my Mac and my iPhone in "System-Update" there are shown "Beta-Updates" as well.

I turned them "off" but want to "hide" the menu item, as it was before I used the "Feedback Assistant".

Can you tell me, how I can "leave" the Beta-Program, so that the "Beta-Update"-menu disappears?

Sorry for my bad english!

Greets, Marcus

[Re-Titled by Moderator]