Conquer Club

I'm having problems leaving my usergroup "the Immortals"

The clan never was too active, and now it's pretty much dead..
I wanted to leave, but I tried to from the Control Panel, it told me I cannot leave my default group.

Any suggestions or is this supposed to be happening?

You can send in an e-ticket or have the new clan make your default their group. At that point you'll be able to drop the old group. You can only have one default group and the leaders shouldn't (but can) set a default.