Every word you’ve ever written is worthy. Everything you’ve ever written can serve a purpose. I know the delete button is tempting, but don’t do it! You might regret it some day. Instead of deleting, do the following:
Can you make your words work with a few simple changes? Give yourself some distance. Move to a different scene and come back to the one you’re not happy with. Has your opinion changed? A first draft is never the final, so don’t expect the first thing you write to be perfect.
If you can’t make your words work for the scene you’re working on, save them for later! Another scene, or a whole other book, might be just the right fit for what you’ve written.
No matter how bad you think your words are, they represent a learning opportunity. Analyse them to find out what works, what doesn’t, and why, or simply save them to see how you’ve improved. People aren’t born with the talent to write, they practice. Seeing how your style changes over the years can be just as informative as what you’ve written.