Related Clues:

• Go backward
• Render ineffective
• Hit 'back'
• Formally withdraw
• Go back a step, in word processing
• Put back the way things were
• Reverse an action
• Reverse, as an action
• Elevator
• Word-processor command
• Free of knots
• Make disappear
• Annul an amendment
• Scrub, as a mission
• Change back