Remove teams and users that aren't defined

[venkatamutyala]

It looks like if teams are added and then later removed from the yaml they don't get deleted out of github. I think having an option to have the yaml under the teams/ folder be source of truth would be preferred for most. This way users don't end up with orphaned teams. Could we add a flag to enforce this type of reconcilation?

[mxmehl]

That would absolutely be an option. The same goes for users that are no members of any team.

For both cases, there is a warning in the output, so at least users of the tool will know about these incidents.

However, I personally don't have a high priority for those issues. If you like, you're invited to add a PR.