I would like to suggest a closing group button. I found some sort of an exploit, that when the owner leaves the group, it becomes unable to use. I am not sure it if is intended or some sort of bug.
The Closing button could be much easier to remove unneeded groups. Because of my unknowledge how to remove it correctly, I had to report the group with the closing request describtion. I apologize for the problem.

I hope that the button will be added as soon as possible

Thank you in advance