How do I remotely track a missing persons Android with GPS I have a family member missing over a week now. How do I remotely track the missing person on their Android and get a GPS location?

I need to use my desktop computer to do the tracking.
If you have access to the Google account on the phone, you can use Google's Android Device Manager to locate the device. This requires the phone to be powered on with location services enabled. This will notify the phone as well. 

If you do not have access to the Google account, you need a preinstalled tracking application, like Google+. Some more examples of preinstalled options:
https://www.cnet.com/news/location-tracking-apps/
http://www.phonearena.com/news/How-to-share-your-location-and-GPS-coordinates-using-your-smartphone_id50312

If you don't have either of these, then you can't use GPS to locate the phone; you need to have the phone service provider locate the phone (provided it's on). This is not a service normally provided to the general public. Get help from law enforcement, a private investigator, or a skip tracer.