### Summary ###

remove a sub-channel within a channel.

### IO ###

```[-ch_name (text) -sub_name (text)]/[text]```

### Description ###

remove a sub-channel given in -sub_name for the channel given in -ch_name. only the channel owner-level(1) and admin-level(2) is allowed to do this. all sessions that currently have this sub-channel open will be forced to close it.