Check out the webpage of Canada Revenue Agency ("CRA") on making changes with respect to a registered charity.  The CRA recently added “Changing a charity’s authorized representative information” and “Changing a charity’s director, trustee, and like official information”, which are available here:

As a reminder, registered charities are often subject to increased CRA scrutiny, even with respect to certain routine matters.  So it is always advisable to check whether there is a requirement to report to the CRA or obtain its approval prior to making any changes.