How can one delete the N numbers on the drop down menu that are no longer useful?
Which drop down menu are you refering to?
Top left box for entering flight # or N #. After you enter N, a menu drops down revealing all the aircraft N#s that you have previously entered/tracked.
That’s probably a function of your browser, not the site. I don’t have a drop sown box there myself.
Highlight the N number and push the delete key to remove autoentries. I am assuming you are working off a Windows based computer.