Forum Discussion
Cannot remove a Guest from a Channel or a Team
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.
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)