The printer needs to be configured for Borderless Printing. Luckily for you, there is a guide explaining how to do this, but you need to make sure that you use the correct paper for this process.
Support page: http://support.hp.com/si-en/document/bpy21049
You can enable Borderless Printing using the instructions on the above page, but your printer needs to support this feature first. Ignore the versions mentioned, because the process is the same. If no menu is found using the instructions, then it means this procedure is not available for your device.