You
            can clear strokes from the canvas that were created using a source
            front or source matte.
         
         WarningClearing strokes
               for an entire sequence cannot be undone.
            
         To clear the strokes associated with
            a source:
         
         
            - In the Sources list, select the source
               used to create the strokes you want to clear.
            
- From the Selection Mode box, select Current
               Frame or Sequence.
            
- Click Clear Strokes.