Yep, once your ad has been running for 72 hours, you can cancel any time. Before that, cancellation is locked so Meta can get the ad through its initial learning phase. After 72 hours, the option opens up in the Status section of the Ads tab on your Link.
How it works
The ad stops running immediately. Unspent credits return to your SubmitHub balance, usually instantly. Anything Meta has already spent on impressions and clicks is non-refundable (those ads already ran).
Need to stop the ad before 72 hours?
Pause it instead. Pausing is available right away and stops the ad from spending. See the "Pausing an ad" article.
Something went wrong? Not happy?
If you're canceling because of an issue (targeting was off, creatives got rejected, results don't look right), reach out before you cancel. In some cases, we can restart or adjust rather than end the campaign.