if you follow only SfB or MS Teams and aren’t deeply involved with Azure AD, you may ask how you can stop seeing some guest access you see in the Teams Account List
For example I’ve access to 4 Teams as Guest, and I want to stop seeing the first.
Well, no, you CANNOT remove yourself from a Tenant you have access as Guest!
Azure Active Directory B2B collaboration FAQs
Can an invited external user leave the organization after being invited?
The inviting organization administrator can delete a B2B collaboration guest user from their directory, but the guest user cannot leave the inviting organization directory by themselves.
At this moment you have to ask to your contact to delete your Guest Account from their AAD.
I think this is something Microsoft should fix/change as soon as possible.
Hope this could help some of you.