No, it's not possible.

One approach would be to create an Adjustment batch with an entry for each Invoice that was posted in the Invoice batch. Each Adjustment entry would be for the full amount of the Invoice and would reduce it to zero.

If the Invoice batch is so large that this is a lengthy process, it may be faster (and cleaner) to restore your data backup. Before doing so, consider how recent your backup is, how reliable it is and what other work has been done since. Make a copy of your current data first.

As Bruce said - it's not possible - and will probably never be. There are too many issues around tax liabilities etc in Adagio Payables and Adagio Receivables to be able to do this with any degree of certainty.

What's the reason you want to unpost a whole batch?