Item Stock Management is where a manager 86s an item or sets a countdown on a limited special, without leaving the POS.
On the Room screen, tap Options, then Settings, then Item Stock Management.
Tap Clear All to empty the screen of tiles when you are done.
Set its stock value to 0.
That last point is the reason to do it here rather than telling the servers verbally. A verbal 86 does not stop the online orders arriving.
Return to the same screen, search the item and set a count above zero, or the count you actually have. Make this part of the open checklist at any site that 86s regularly, or yesterday zeros will still be in place today.
Source: Global Payments Genius POS User Guide. Newly built article, pending review.