Acknowledgements: Hat tip to Eric Hemmeter on the MacAdmins Slack for this command.
If you want a command that will add back the Wi-Fi service if you deleted it and now want it back, here it is:
networksetup -createnetworkservice Wi-Fi en1
That’s assuming the output of networksetup -listallhardwareports
has a hardware port of Wi-Fi with its device being en1 (could be en0, for example).