What is the ruling on placing a magical charm in vinegar to nullify it, and will Allah accept the repentance of a woman who did that out of remorse?

You must repent to Allah with sincere repentance for going to the sorceress. Sincere repentance erases the sins that preceded it, as the Prophet, peace and blessings be upon him, said: "The one who repents from a sin is like one who has no sin." You should destroy this work by burning it or putting it in water. As for vinegar removing its effect, we have no knowledge of that.