TweetDeck uses Deck.ly to allow users to write tweets longer than 140 characters. The problem you experience is because Deck.ly does not work as expected. Deck.ly is a service of TweetDeck (if you try to open deck.ly from your browser, it redirects to tweetdeck.com). You cannot change it from TweetDeck settings, but you can disable it. Just uncheck the following option in settings:
Best Answer
Click the right-most icon -
And I hope @Newsweek is your own account. Or else you cannot delete the tweet.