If you wish to clear your wall from all the post somehow same like you clean your home , here is a simple and fast way to perform that in minutes instead of manual clicking post by post to delete all .
You would need a Firefox Browser and install the Greasmonkey Plugin first
After go to user scripts and install these one , in the Tools menu you should see now Greasmonkey and User Scripts perform the new installed script to delete ALL your wall Post activities just everything . to be faster you should click on Older Post on the button of your wall several times . It delete only what is visible to you. It takes about 10-15 minutes for 2 years posts. I would recommend that you download your Facebook backup before just in case you would like to take a look at some old posting
Get a copy of the data you’ve put on Facebook.
Facebook Backup you find that in Account Setings – Download your Information FB need some time and will inform you via email when its ready to Download.