In the Manage Ads page in a campaign, click on the down arrow to the left of the ad and choose Archive. Once an ad is archived, you will be able to see it and view its statistics from the time it ran, but it will not run and you will not be able to re-activate it.
To see the archived ads, click the Filter dropdown and select Archived. Choose Yes to see archived ads.
To view reports click on the down arrow to the left of the ad and select View Report.