Q: Keeps disconnecting from the USB port on ho- Should I have not "trusted" my work PC?

My iPhone 6+ was working fine until something changed on the device or my Windows 7 PC at home.

It keeps connecting and then disconnecting from my PC when plugged into the USB port (where it was connecting just fine before).  This repeats every 2-3 seconds.

The one thing that changed is that during the workday, I took it to my work PC (to plug in and charge).  I chose to "Trust" my work PC when prompted by the iP6+ even though I need not have done so.

Maybe that was the cause of the iP6+ now disconnecting from my PC at home every 2 seconds.

How do I "undo" my decision to Trust my work PC?

How do I prevent this "connect-disconnect-reconnect" cycle on my home PC (where I use iTunes 11.4.0.18)?

Thanks.

Aloke