Regarding permanent deletion of yahoo messenger chats from my computer?

I want to permanently delete Yahoo messenger chats that i had.I worry though i have uninstalled it from disc C it still can be retrieved.My ex had bumped in the chat.So i deleted my yahoo account as well.I opened a new one now.I just want the yahoo messenger chats permanently deleted from my account and computer hard disc.Does my new account on the same computer help retrieve my yahoo messenger chats of the deleted account.My deleted account is still exists in Gmail account and it worries despite i permanently deleted it.The funny part is i cannot acess my deleted account on Yahoo sign in but it exists in Gmail sign in.