Here are some great sites that let you delete all of your Twitter Tweets in one go.
Browse all tweets fast Browse or find tweets easily even if it is 2 years old. Select date or type and see your tweet history in a second. Everything is 1 click away Select/deselect many tweets with 1 click and delete multiple tweets with another click. Launch automatic tweet deleting Set up an automatic tweet deleting in seconds and keep your twitter account clean continuously.
TwitWipe is a tool to wipe or delete all your tweets in one go. You may need to do this to start over, to clean it out before handing the account over to someone else, or maybe you’ve just realized how nonsensical your tweets are! Whatever the reason, TwitWipe is the answer!