python says it is running with elevated access but it is still returning an error?

Instead of this:

process = Popen([r"C:\Users\PC\Downloads\TCPView\Tcpview.exe"], stdout=PIPE)

Try this:

process = Popen([r"C:\Users\PC\Downloads\TCPView\Tcpview.exe"], stdout=PIPE, shell=True)

Namely, set the shell parameter to True.