How can I remove Crayola Washable Window Markers or Window Writers from glass, Plexiglas or mirrors?

Spray the window with glass/window cleaner as you would to wash the window. Then, follow-up with a quick wipe by using a dry towel. You could also use a water-dampened towel and follow-up by wiping with a dry towel. WETTING THE AREA WITHOUT USING A DRY CLOTH WILL SMEAR AND SPREAD THE RESIDUE RATHER THAN REMOVE IT.