You are free to leave your metro at any time.

Just sign into Xanga, and visit the metro you'd like to leave.

See on the upper left, where it says:

Members:
» Leave Metro

Just click on "Leave Metro".  You'll be asked to signin, and then to confirm that you really want to leave your metro.  This confirmation helps maintain your site security.

Once you've confirmed that you want to leave, your metro membership will be deleted.  If you are the last member to leave a metro, it will be deleted from the Xanga Metros Directory.