This map was created and can be edited at http://simplemaps.com/custom/usgrid/uX6M2W27
To remove the "Simplemaps.com Trial" text, purchase a map license. Then, register your license at the link above (Options > Register Purchase). Or, simply replace the usgridmap.js file in this folder (trial version) with the usgridmap.js file that you are emailed (full version).
To learn how to install this map on your web page, see the Documentation.