Is an acting 1SG authorized to pull leave forms once they have a control number, or is that done by higher than him?

Did the 1SG sign the leave form- NO, only the Cdr can pull leaves because he signed them. Tho e careful of crossing a 1SG- they have long memories.

No 1SG, acting or otherwise, has the authority to deny someone leave, either at the request stage or after it has already been approved. Only a commander has that authority, and a 1SG can only recommend approval or disapproval. With that being said, many commanders will defer to their 1SG's recommendations. I would make sure that the commander is aware of the actions being taken by the Acting 1SG, and that he/she approves of his pulling back the leave form.