Sign in to the Facebook account you use in conjunction with "Facebook Ads." Click the "Advertising" link at the bottom of the screen, then click "Manage Existing Ads."
Open the ad campaign that contains each ad you need to cancel. Click the individual ad you want to cancel.
Hover your mouse over the ad's "Active" status and open the drop-down menu. Click "Pause" if you want to temporarily remove the ad with the possibility of re-posting it in the future. Alternatively, click "Delete" to permanently cancel the ad.