Firefox Tip: How to Delete History from Forms and the Address Bar

When browsing the web, you often need to input URLs in the address bar and enter text into forms. No matter what you type, Firefox faithfully records it for your convenience to use again.

However, we might make mistakes or there may be some content we don't want others to see, which means we need to delete these records. Although we can use Tools -> Clear Private Data to delete all records, what if I only want to delete one of them?