Dye stains of any type can often be a real challenge to remove from cloth materials--including canvas shoes. But it is possible to get dye out of cloth or canvas shoes. The key to remember with any stain treatment is to address the problem as soon as it arises. Immediately treat the denim dye stain. Do not wait a few days, or worse, several weeks. The less time the denim dye has on the shoe fabric, the better the chances for removal.
Blot the denim dye area with paper towels. Try to absorb as much of the dye out of the shoe fabric as quickly as possible.
Remove any shoelaces or other accessories.
Completely cover both shoes with a heavy duty liquid detergent. Cover the entire shoe, not just the denim dye stain area. Allow detergent to remain on the stain for approximately 10 minutes to pre-treat the stain.
Turn a sink faucet on to run cold water. Completely rinse the heavy duty liquid detergent out of the shoes with the cold water. Keep rinsing until the shoes have no liquid detergent left on them.
Mix one part color-safe powdered bleach and four parts cold water in a sink. Place shoes in the sink, making certain the shoes are completely immersed. Soak shoes overnight in this solution.
Remove shoes from the sink solution and rinse thoroughly. Allow to air dry. Return shoelaces and any other accessories taken out in step 2.