My staining agent is Metha+Gla Ace acid+H2O+ CBB and i keep for 45 - 60mins..and destaining agent is Meth + Gla Acet acid+ H20 and i keep for 8 hrs to over night..
Destain it using above mentioned destaining solution for a longer time. You can also put it inside the oven for 45 seconds to destain the gel fast but make sure the container carrying the gel should be of good quality.
You can also microwave for 20seconds with 5min room temp intervals for faster results. Test it with the destain solution first to ensure there is no splashing.