Sometimes, when you try to delete milestones from your project, you will notice that the delete icon beside the milestone you want to delete is grayed out.
This article describes the process of deleting and restoring milestones in FogBugz.
Navigate to the avatar menu and click Projects.
This will display all the projects. Click the edit icon beside the project that contains the milestone you want to delete.
It opens the project details where you can see the milestones associated with this project.
Note: For assignable milestones, the delete icon is grayed out. If you click the delete icon, the following error will be displayed: Can't Delete Active Milestone.
Click the edit icon beside the milestone you want to delete.
In the Edit Milestone window, select the No radio button for the Assignable field and then click the OK button. This will render the milestone as unassignable.
A list of active milestones and a link to Display Deleted and Unassignable Milestones is displayed.
Click the Display Deleted and Unassignable Milestones link to view the unassignable milestones also.
Note that the delete icon with the unassignable milestone is now clickable. So, click the delete icon beside the unassignable milestone that you want to delete.
Restoring the Deleted Milestone
If you want to restore the deleted milestone, click the undelete icon beside the deleted milestone.
To use the milestone again, click the edit icon, select the Yes radio button for the Assignable field, and then click the OK button. This will restore the milestone completely, and it can be used again within the project.