It IS possible, although I don't know how to go about it. I used to be in the Ten Ton Hammer guild on Blackburrow server. The guild was de-affiliated with the web site, so was renamed. I was not involved in the name change though being only an officer, not a guild leader.
Perhaps it's only something SOE does for legal/policy reasons.
As it happens, I waved goodbye and took a free transfer to an EU server a few months later.