Then let this extension do these work for you.
Simply and effectively remove all messages from your FB account. You can also select several specific messages and then delete them in one click.
Once you install this extension, go to Facebook and look for the extension icon in the top right of your address bar. Click the icon to open the conrol panel. Remember, to ensure the work of the extension need to be authorized on Facebook.
Use this extension at your own risk. Please delete your messages carefully. The developer is not liable for any moral or material damage incurred to you related to the removal of messages by this extension. Using "Delete All Messages for Facebook™" Chrome Extension means that you agree to these terms.
Facebook™ is a trademark of Facebook ™ Inc. This extension, namely “Delete All Messages for Facebook ™" has no connection to Facebook ™ inc.
An easy-to-use interface will speed up the process of deleting all messages.