First question - why do you want to remove the Night Mode? (just curious)
The IDE web interface will be going away soon so the ability to create/remove Modes will disappear. Unless that feature gets added elsewhere such as the app, my.smartthings or CLI. Currently, you can only edit Mode Names in the app… you can’t add/remove. Now sure about what you can or can not do in CLI so hopefully others can respond if possible there.
You can add them through the new interface, which is accessed either with a program that runs on your computer, the CLI (command level interface). Or, if you would rather just use a webpage, you can use the API + project I mentioned from a community member.
It’s certainly not as convenient as the IDE was, but the functionality is still there.
I imagine there’s a limit on the total number of modes you can have, but I don’t know what it is.
The SmartThings API can manage Location Modes but it is not documented in the API reference. Similarly the functionality is in the Core SDK which powers the CLI but hasn’t been exposed as CLI commands.
I don’t know if there is any significance to this, or to the limited functionality provided in the client apps.