There are a lot of reasons to deactivate items rather than delete them. Not the least of which is the potential to have older editions show up in your store at a different cover price alongside a new edition with a higher price. You may still need to find that old edition.

 

But if you are confident in what you want to hide, you can hide inactive items from search results within your transactions. Just navigate to SETTINGS>TRANSACTIONS>includeInactiveOnTRNSearch and turn the setting off.