Managing the channel and attempting to remove guest members by pushing the X simply results in the X returning after a second or two and the guest member remains.
That isn't how it is supposed to work so that is frustrating. If you continue to see this, please go to answers.microsoft.com so they can help you troubleshoot.
@MarcPatti380 , if you cannot remove a guest user from a group where you are the owner, then you could try doing that from the mobile phone (that was the only way it worked for me, not having an Azure admin account, but as the owner of the group)
