We will access from:

Finance --> Stock control --> Products

We will see a window with the list of all the articles we have available.

Click on the "Edit" button of the product we want to discard:

Once inside the product tab we have chosen, we will click on "Stock" from the menu on the left, and in the window on the right we will click on "Stock available" and on the button "Set stock":

When we open the file of the stock, we must choose the Warehouse from which we want to discard the product, the quantity and in the dropdown you have to indicate the option of "Disposal of products" we will see as it appears next to the quantity the current stock that will remain.

Click on "Update" and we will have already discarded it.