Section 5303 Of Chapter 3. Ownership Between Parties And Their Creditors And Successors From California Probate Code >> Division 5. >> Part 2. >> Chapter 3.

. (a) The provisions of Section 5302 as to rights of survivorship are determined by the form of the account at the death of a party.
  (b) Once established, the terms of a multiple-party account can be changed only by any of the following methods:
  (1) Closing the account and reopening it under different terms.
  (2) Presenting to the financial institution a modification agreement that is signed by all parties with a present right of withdrawal. If the financial institution has a form for this purpose, it may require use of the form.
  (3) If the provisions of the terms of the account or deposit agreement provide a method of modification of the terms of the account, complying with those provisions.
  (4) As provided in subdivision (c) of Section 5405.
  (c) During the lifetime of a party, the terms of the account may be changed as provided in subdivision (b) to eliminate or to add rights of survivorship. Withdrawal of funds from the account by a party also eliminates rights of survivorship with respect to the funds withdrawn to the extent of the withdrawing party's net contribution to the account.