You manage your company's positions from within Position settings. If there is a position you no longer require to be an option to assign to employees, you can delete it.
Click your name in the top right-hand corner, then click Settings.
From the general settings menu, click Employee data.
Click Positions.
Click the trash can icon next to the position you want to delete.
Click OK to confirm the deletion.
📎NOTE: You can't delete a position that is currently assigned to employees. You must unassign an employee from a position first to delete it.