put it in the washer- warm water and detergent- wash it- rinse and see if the water is clear- if not= wash again-
you can add retayne- which sets dyes- you can toss in color catchers- to catch the fugitive dyes-
if after 2 or 3 washes it still bleeds- put it aside and use something else- some fabrics run until there is no color left- some just have some excess dye and will stop after a couple washes.