Your Facebook Wall is where you announce events, thoughts -- or just about anything else -- and your friends drop by to say hello or leave a link to a cool site. A friend on Facebook might also post a picture to you Wall he thinks you might like or find interesting. Occasionally, though, a friend might post a picture you do not like or want other Facebook friends to see. If this is the case, you can delete an unwanted picture on your Wall – even if you did not upload it.
Navigate to the Facebook.com site and log in with your email username and password.
Scroll down to the link posted by your Facebook friend that contains the photo you want to delete.
Position the mouse cursor to the right of the name of the Facebook friend in the post. An "X" appears to the right of the cursor. Click the "X," then the "Remove Post" link.
Click the "Remove Post" button in the popup confirmation window. The post and unwanted picture disappears from your Facebook Wall.
Prevent Posting to Wall
Log in to your Facebook account. Click the "Account" drop-down box at the top of your profile page, then click "Privacy Settings."
Click the "Customize Settings" link near the bottom of the "Choose Your Privacy Settings" page.
Scroll down to the "Things others share" section. Click the "Enable" check box next to the "Friends can post on my Wall" label to remove the check mark.
Click the "Profile" link at the top of the page to return to your Wall and save the settings changes.