Related Clues:

• Counter
• Repair damage
• Invalidate
• Clear the slate
• Remove evidence of fallibility
• Do a classroom chore
• Go back to square one
• Use the backspace key
• Clean boards
• Shake an Etch-a-Sketch
• Answering machine button
• Bring to naught
• Annul
• Set right, maybe
• Remove from the blackboard