Users with Manage Role permissions can delete roles from projects.
Note: All history for the role and associated people is lost once the role is deleted. This cannot be undone.
Project > List
With the project in context, select the on the right-hand side of the role and click Delete role.
Project > Gantt
Under the Gantt Settings, is the ability to customize the Project Gantt view to help condense relevant information. Also, filter the roles that are needed for your request.
On the Project Gantt view, hover over the role to delete and click on the icon. Select the Remove Role button in the role window and then Remove to confirm.