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 triple dots on the right-hand side of the role and click Delete role.
Project > Gantt
Under the Gantt Settings, you have the ability to customize the Project Gantt view to help condense relevant information. You can also filter the roles that are needed for your request.
On the Project Gantt view, hover over the role you wish to delete and click on the pencil icon. Click on the Remove Role button in the role window and then click Remove to confirm.