We haven't had any reports of similar issues, 665.
Let's get this sorted out so you can delete a bill successfully. We can start opening our account through a private browser to check if this is a cache-related issue. Please use these keyboard shortcuts depending on the browser you're using:
For Chrome and Firefox, press Ctrl+Shift+N
For Safari, hold down Command+Shift+N
Once done, try deleting the bill once again. If you're able to delete it, let's go back to your regular browser and clear the cache. This process will eliminate browsing history and start the program fresh. As an alternative, you can also try using other supported browsers.
Here are some articles you can refer to learn more details about Bill in Quickbooks Online: