According to How to Clean Stuff, the process for removing Wite-Out from clothing involves getting the hardened Wite-Out material to turn back into a pasty substance. This makes it easier to remove without damaging the fabric.
To get the Wite-Out to come out of clothing, the Wite-Out needs to be scraped off as much as possible. After scraping, spray either WD-40 or Windex on both the Wite-Out and the under side of the clothing where the Wite-Out is located. Rub the chemical in thoroughly but gently. Let the clothing sit with this spray on it for a few minutes. Then, gently scrub the Wite-Out off with a soft cloth or sponge. Keep the area wet by adding more spray if needed. The scrubbing may take a bit of time to get the Wite-Out completely off the clothing. After removing the Wite-Out, wash the area where the Wite-Out was located with soap and water, or just wash the piece of clothing the same as any piece of laundry. This process removes any excess residue that did not come out in the scrubbing process. Goo Gone and rubbing alcohol are other options for removing the toughest Wite-Out stains from clothing if the other method fails.