You can reverse the erroneous stock taking on the stoct taking window, entering a decremented value in the Counted in the Whse column. In the Inventory Posting window you can change the decrease account to the previous increase account to neutralize the booking. It will be exact neutralization only if the cost value of the item did not changed. Otherwise you can use manual booking to a full correction. You can try it in a copied data base.
(Because the new versions does not use the OINM table, I can not see the transaction types in it.. You can try and see in a test version.)