You can delete a milestone in two ways. First way can only be accessed through the Masterplan View. To delete a milestone, click on the Menu (three dots) beside the milestone name, and click Delete. Click Delete again to confirm your action.

Another way can be done through both Masterplan and Lookahead gantt chart. Single-click on the milestone to open the widget view, and click delete. Click Delete again to confirm your action.

Watch the video below to learn how to add or delete a milestone: