On the Workflow page on the workflow chart, select the plus (+) icon.
In the Workflow action dialog box, select Assign or revoke role.
From the Action list, to assign a new role, select the Assign a new role option. Otherwise, to revoke a role, select the Revoke an existing role option.
From the User list, select the Triggering instance.owner option or whichever you require.
From the Role list, select the role you want to apply and click ADD.