Due to differences in the architecture of Teams standard and private channels, once a channel is created, you can't change from private to standard, or vice versa.
To change a channel, delete the old channel, create a new channel, and select Standard or Private at creation.
Important: Your admin manages whether you can create a channel or select Private or Standard. Talk to your admin if you need to do this and can't.
For info on creating a new channel, see Create a channel.
