To pre-approve or block all ads for a particular AdWords account, locate an ad related to that account in the Ad Review Center. Hover over the ad, click the gear icon and choose either “Pre-approve this AdWords account” or “Block this AdWords account," depending on your preference.
You can view your lists of pre-approved and blocked AdWords accounts later by visiting the Settings subtab in the Ad Review Center.
Note that when you block AdWords accounts whose ads you've previously approved, it may take up to a day for them to stop appearing on your website. You'll also notice this delay when you approve AdWords accounts that you've blocked in the past.