Tips for removing methyl blue stains?

Hi, we've had a bottle of 1% methylene blue smash on the lab floor and up the (freshly-painted!) wall. Bleach soultion has faded it a bit on the floor, but made no difference on the wall. Any ideas? Please and thank you!
You could try - Making up a solution containing 1 part vinegar (acid) and 1 part saturated Vitamin C (reducing agent), then rub that into the stain.