You can run scripts that will delete your own old tweets, however as much as we may want it we don't have the ability to delete other people's tweets
In this case whomever is behind the account removed their old tweets
twitter.com/search?q=from%…
twitter.com/search?q=to%3A…
In the search we can see old handles the account may have had based on the @'s
if we check the html for that page and search for the id from the tweet above we find that sure enough same
So please unfollow, retweet, and let anyone you know following it know to unfollow it