Can the admin release the funds before the clearance period has passed?

Yes, as admin, you can set the clearance to 0 so, for all of the future jobs, sellers will have the money right away (as soon as transaction has been marked completed).

If you want to keep the clearance and release the funds only for a certain order, you can go to Admin > Orders > The specific order > Click clear now button.

To use this option, the orders need to be marked as delivered and completed.