Device Templates were moved in NCM 7.7. It's located:
Settings > All Settings > NODE & GROUP MANAGEMENT > Manage Device Templates
I'll submit in the humblest, most friendly way possible, that nothing beats RTFM for finding the answers to your needs in a thorough manner.
Some M's are not well written.
Some users advance more quickly with hand-holding.
And "RTFM" is often a snarky response that comes far too quickly.
But occasionally, it's exactly the proper course to take.