Team owners get to decide which team members can delete and restore channels.
Tip: If you’re considering deleting a channel because you’re being inundated by notifications about new messages, you can instead just turn off notifications.
To delete a channel, go to the channel name and click More options 
> Delete this channel.
Keep in mind that once you delete a channel, you also lose its entire conversation history. However, the OneNote sections associated with that channel will still show up on your team's SharePoint site.