Instructions
Log into your Facebook account in a Web browser.
Click "Account" in the upper-right of the screen, then click "Privacy Settings."
Click "Edit Your Settings" under "Apps and Websites."
Click "Edit Settings" in the "Apps You Use" section. Scroll down to the row containing "FarmVille," then click "Edit."
Click the drop-down menu next to "This App Can Share With," then click "Customize."
Enter the names of the people who you don't want to see your FarmVille updates in the "Hide This From" section. Click "Save Setting" to save your new settings.