A service body’s bylaws, approved by the trustee reviewing them, always include provisions for amending them. If a bylaw no longer works, it needs to be amended according to the service body’s agreed-upon policies and procedures. It is possible that such a change might be better included in a more easily amended policies and procedures manual. (See this question for more information on policies and procedures manuals.)
Once the amendment process has been accomplished, the service body’s updated bylaws are to be forwarded to the World Service Office, which then arranges for region trustee liaison review and approval.
Source: Document Library on oa.org under the category “Bylaws”: Bylaws and Policies and Procedures for Service Bodies