Teams creates a General channel for each new Team. Hiding the channel was previously not possible.
Added to the roadmap in January, Teams can now hide the General channel. The option should be available by the end of March.
There is a special case when a team only includes the General channel. In such cases, Teams will hide the entire Team. Teams informs with a short message.
A hidden General channel can be shown again as usual by right-clicking on the hidden channel or in the Team management.