The process for removing a director will depend on the provisions of the company’s constitution (which would generally provide the shareholders with the right to remove directors by ordinary or special resolution). If there is no company constitution in place, section 203C of the Corporations Act is a replaceable rule which allows the shareholders to remove directors by ordinary resolution.
There is no requirement in the Corporations Act for a director to be notified of their removal, however the prudent approach is to ensure the director is informed in writing so they are on notice that they no longer hold the position or have authority to act on behalf of the company.