Sysmon v15.11

Getting same error/results when I attempt to uninstall version 14.16.0.0 from existing Windows workstations as I got when first attempted to update to version 15.0.
When attempting to update a machine, I first run [Sysmon64.exe -u force[.  This executes successfully.
I then attempt to install/configure new version of Sysmon using [Sysmon64.exe -accepteula -i C:\Windows\Sysmon.xml], but it exits with code 1053.
Further attempts to uninstall sysmon retun exit code 5 with this output:
       Stopping the service failed:
       The system cannot find the file specified.
       DeleteService failed:
       Access is denied.

Am I doing something wrong?