Here's how to delete a playlist:

1. While logged in to your Glitch account, click on your avatar which is located at the top-right corner of any page on glitch.com

2. In the popup menu, click on your avatar.  This will take you to your profile page.

3. Click on the playlist that you want to delete.  This will take you to the playlist page.

4. Click Delete playlist.

5. A confirmation popup will appear.  If you are sure that you want to delete the playlist, click the Delete button.