Once you’re here, make sure that Enable Custom Content Mods and Script.
Then, select Game Options, and then Other. Start it up and on the main menu, click the three dots at the top right-hand side.If there is a class named mod_(one you want to remove).class, delete it. Copy classes from the vanilla minecraft.jar over classes from the mod if they have the same name. Look inside the mods you want to remove and note the classes they include. Move your minecraft.jar and force update.