Related Clues:

• Clear the board
• Run a cloth over
• Erase
• Remove, as marks
• Do away with
• Piece of absorbent material
• Undo
• Remove a slip?
• Remove from a disk
• Nullify
• Take-out order?
• Clear, as a disk
• Wipe, as a blackboard
• Make blank
• Prepare for reuse, perhaps