As much as the Internet has grown and changed over the decades, one thing remains the same: when you send a message, you cannot take it back. Whether it is email, a forum or Facebook, it is the same. However things are somewhat different with deletion. Deleted email usually goes to a trash folder, where you may be able to retrieve them if you change your mind. Facebook gives you the choice to archive messages, including sent items, instead of permanently removing them.
A Facebook user can send messages directly to other users via Facebook's internal messaging system, called Facebook Messages. The Messages feature is similar to private messaging in forums. You can send, delete or archive messages or entire conversations. Using this feature, you can also send and receive email like in a traditional email system if you have set a Facebook email address.
The delete option is partially hidden from view in Facebook Messages. To delete a message that you had sent, click the conversation it belongs to, click the "Actions" button at the top right and select "Delete Messages." Click the sent message and click "Delete Selected." This permanently erases the message from your account. However it does not stop that message from being delivered to the recipient. Once you have sent a message, it cannot be undone.
The Messages interface favors archiving messages over deleting them. When you click the "x" button next to a message, Facebook archives the message. It disappears from view but is not deleted. To see archived messages, click the magnifying glass button and select "Archived Messages." Clicking the arrow button on a message sends it back to the main folder.
Sorting through Facebook conversations to find sent messages can be difficult. To view only your own messages, click the magnifying glass button while in Messages and choose "Sent Messages." To look for a specific message, enter your search terms in the search box next to the magnifying glass. If you want to narrow your search to a particular conversation, select that conversation first.