In one of the previous posts under a similar heading, the person suggested creating a new duplicate route and then going to the bottom of the new course screen (before saving), and setting the VP average speed to 1 mph (or kph). As you do a ride on that course, yo soon will see the VP disappear off the left horizon.
I followed those instructions, but noticed that you may not have to create and save/rename the new identical route (and delete the old one). If you hit the 3 dots at the bottom of the old route screen, you will see popup choice that allows you to edit. From there, you can scroll down to the speed partner (VP) and reset the default speed from 16 to whatever you want, like 1 mph.
I haven't followed through and tried this on the road yet, and I stlll need to synch to my device. But my fingers are crossed.