If you delete a boosted post on Facebook, there’s only one reason you will be charged. If you haven’t paid the ad spend accrued from running the boosted post before you deleted it, then yes you will still be charged because you haven’t reached the end of your Facebook ads billing cycle.
If you only scheduled the boosted post and then deleted the post before Facebook began promoting it, then no you will not be charged.
If you want to learn more about how billing works we recommend taking a look at the Facebook Ads billing help page.
