You can actually accidentally remove yourself from group as only member.
I have lost control over group on gitlab.com. Now the group is in "Limbo". No one controls it.
What's happened/how to replicate?
I wanted to add some members to the group since the other members names are similar to mine I accidentally added myself along with others as a master of the group. In that point group didn't have any owners. I've tried to remove the master level from myself with clicking the red minus. I thought it will automatically return owner status. But I wasn't the member any more. Other guy was thinking if he also remove himself the group will destroy itself, but NO. He also removed himself :)
Now the group hangs in the middle air, without owner and I CAN NOT create the group with the same name as it says the group already exists. So there it is.. the statement od the permissions.md file "Any user can remove themselves from a group, unless they are the last Owner of the group." is NOT VALID :)