How to Delete a Retweet From Twitterby Nick Peers
When you retweet something, you basically repost the original tweet so that all your followers can benefit from the information. Although sometimes people start a retweet with "RT," you can also retweet a tweet by clicking the "Retweet" link. The "RT" method is not officially supported by Twitter. If you no longer want to share someone else's tweet, you can delete it from your Twitter account.
Remove the Retweet
Log in to your Twitter account and click the "Tweets" link below your name to view all your tweets. Retweets appear in the same section. Retweets have a green arrow in the upper-right corner of their box. Locate the retweet you wish to delete and then click the "Retweeted" link below the tweet to delete it. The "Retweeted" link changes to a "Retweet" link.