If you want to delete all Facebook message then you have to delete single messages because Facebook won’t provide a way to select all message and delete all of them at once. In any condition if you want to delete all Facebook message and make Facebook Inbox zero then you have to put lots of effort and very irritating if you have lots of messages.
So there is a script that can delete all Facebook message with the single click and make inbox zero. You have to execute this script from URL in chrome and for Firefox user have to execute it via Web Console, which activates by pressing Ctrl+Shift+K.
Also check out: How to delete kik account easily.
Since it is related to script and executing a script for a basic computer user may be a difficult process. So I am trying to simplify the whole process. You may know that script can be executed from bookmark bar of browser so it become easy to execute for the basic user and it will work in all browser in a similar way. Follow the Bellow guide to delete all Facebook messages.
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Step to delete all messages on Facebook
Step 1: Drag and drop below Bookmark to your Browser Bookmark. To drag and drop bookmark you first need to enable bookmark bar in your browser.
For chrome press Ctrl+Shift+B (Windows and Chrome OS) and ⌘-Shift-B (Mac)
For Firefox visit this Page.
Step 2: After you drag and drop the above bookmark you may see small ICON is created on your Bookmark bar.
Step 3: Once you completed above process now go to Facebook Inbox. Once page opens just click the Bookmark you have drag and drop. after click it will delete all your Facebook message. Before clicking make sure because you won’t able to recover your message again in any case.
Step 4: After that press Ok option on pop and then press Delete Conversation button to complete the process if you won’t press Delete Conversation option then your all messages reappear in your Facebook Inbox.
If you are not getting a chance to click on delete conversation Button then repeat the same activity again.Consider you click on bookmark it deletes all messages but messages appear again then click once again on Bookmark it will delete all message again and this time message will not appear again.
Video Tutorial To Delete All Facebook Messages.
Source and script are created by Mikisoft. You can find the original script on their website.
Update: 23 Feb 2013 now script is working properly. Thanks Alex, to fixing and providing working Script. Here is Link to the working script which is provided by Alex http://pastebin.com/nwjkSXDw .
Related: Create an RSS feed notification for Facebook notification.