CPSU rules say that
In order to resign from the union a member must deliver to the Branch Secretary a notice of resignation in writing, such notice to take effect at the end of two weeks after the notice is received by the union.
We will accept emails addressed to firstname.lastname@example.org, faxes to (03) 9662 4591 or letters to PO Box 24233, Melbourne, VIC 3001. Please address your resignation letter to "The Branch Secretary", and note that a two weeks notice period applies.
We like to know why people are leaving the union, so it would be appreciated if you could include an explanation in your resignation notification.
If you are retiring from the service, note that you may wish to transfer your membership to our Retired Officers Division rather than leaving us completely.