There are 3 ways to hide a product from your store:
Click the slider in the top left to hide the product from view. This is best if you're only hiding the product temporarily and want to put it back in your store later.
Click the button further down in the left-hand sidebar to retire the product from your store, but still keep all the information you put in. You can reverse this later if you want to.
Click the button at the top of your product to delete it completely. This will remove all the information associated with the product and it will be permanent, you won't be able to recover it later.