A waste disposal system with a waste receiver for receiving pharmaceutical waste material. A locking assembly is secured to a fixed surface and actuated from a locked configuration to an unlocked configuration. A lock cylinder of the locking assembly may extend forward of a front wall of a receiver body of the waste receiver to engage a locking feature of the cover in the locked configuration. A cover retention feature may prevent axial decoupling of the cover from the receiver body. An engagement feature is moved to be disengaged from the receiver body, and the receiver body is moved away from the fixed surface to disengage the locking assembly from the cover. The cover is decoupled from the cover retention feature, and coupled with the receiver body to seal the pharmaceutical waste material. The locking assembly may be removed from a lock passageway for disposal of the waste receiver.