Found an older Synaptics driver and changed the driver and rebooted.  Now the touchpad appears as the mouse in the control panel.  The mouse/touchpad control is in the status line and can now activate or deactivate the touchpad when USB mouse is inserted.
My Dell Inspiron touchpad shows as a PS/2 mouse. I want to disable the touchpad when I have a USB mouse but the Synaptics drivers have been replaced by Windows 10.  I does not show any options in settings to disable the touch pad only to adjust the sensitivity.
Dell 11 3186 touchpad shows as ps/2 mouse cannot disable touchpad