Section 177 and Section 178 of the Planning and Environment Act 1987 (Vic) outlines how you can amend or end a Section 173 Agreement.
One method is by obtaining written consent of all parties. However, this can take time and may be difficult to achieve if there is opposition or many parties involved.
If this is not possible, you can apply to amend or end a Section 173 Agreement with Council, and have it removed from the land title.