Red Wipe - http://www.redwipe.com

Erase Your Reddit History

Red Wipe is a utility designed to automatically remove the last 1000** your Reddit posts, and all comments permanently. Reddit has stated in the past that even when you delete your comments and posts the last copy is saved on their servers. This applies to when you delete your account as well. Red Wipe will edit all text comments and posts to random data before deletion. This may prevent the original messages from being recovered.

As suggested by gsuberland, "People should also be aware that Reddit comments can and will be indexed by third parties, including Google and Wayback. There are also other services out there designed to specifically "undelete" reddit threads. While this project is a good start, your deleted data may still be accessible elsewhere."

**This is due to a limitation in the Reddit API.