What do i do to get rid of the sulfur smell in my betta's fish bowl?

my betta fish is a red male i got him about a month ago and recently for the first time i used a shock tablet wen i cleaned his bowl i also have a live plant in with him and i take out about half the water everyday and clean the bowl well once or twice a week depending on sediments in the bowl. last time i used a shock tablet and i had never used one before and 2 days later my bowl stunk like a sulfur dumpster filled with baby diapers i washed the rocks over and over and cant get the smell out im wondering if anyone has any ideas to help me get rid of the smell and keep it away without harming my pretty little baby Benjamen the betta