Sounds like a bit of a Spring cleanup happening in your QuickBooks Desktop company file. Clearing out reports you no longer need is a great idea for keeping organized. QuickBooks Desktop doesn't give you to option to delete built-in reports, but if you've got memorized reports to take care of, it's just a few easy steps that you can follow below.
Here's where I pulled those instructions from: Create, access and modify memorized reports
I'll be around if you need anything else. Don't hesitate to reach out. :)