If you need to clear a space in your inventory fast, like if a monster just dropped something, you can delete it. This will not give you gold, like if you sold it, but it will immediately get rid of it. To do this, go to your inventory and click on the item you want to delete. At the bottom right corner of the item's description, there will be a green button with the recycle sign. Click on it, and you will be given the option of deleting the item.