To stop selling an item, go to Products > Products, then click the ellipsis next to the product you want to stop selling.
Click Edit next to the variant you wish to deactivate.
If the price is the same across all locations, deselect Active.
If the price varies by location and you want to stop selling at all locations, change the pricing from By Location to All Locations, and select "Yes, override". The status will automatically update to Inactive, removing the variant from the POS.
If you only want to stop selling at specific locations:
Click the variant you want to edit.
Scroll to Locations.
Deselect the location(s) where you no longer want the item to be sold.
If all variants of a product are inactive, the product will move to the Inactive tab of the product catalog. If even one variant remains active, the product will continue to appear in your Active At My Location tab.