Glide wax is usually sold in a smaller block than in the picture but you can find large blocks for more economic group use.

After ironing the wax in and allowing it to cool, you scrape it off with a plastic scraper working from tip to tail.  Take as much off as possible, ensuring the central groove is free of wax, then brush off the remainder.  Use long strokes and stop when there is no more wax dust coming from the ski.