How can I edit the URL of a home screen bookmark?
I havent been able to find an intuitive way to modify a desktop shortcut's URL, but I have found a workaround for the problem. 


Put your phone in airplane mode and disable WiFi to turn off all internet access
Open the Chrome browser
Type in the URL you are trying to set a shortcut for
Press enter and the browser will alert you that you are currently in an offline status
On Chrome, click the settings (hamburger) button
select add to desktop

You will now have a shortcut on your desktop that refelcts the URL that you have just entered into Chrome
Turn off airplane mode and you're golden.

This applies to Android Marshmallow 6.x as well as Nougat 7.x. It may also apply to older versions as well