According to the recently updated documentation (https://dev.twitch.tv/docs/api/reference/#modify-channel-information ):

To remove all tags from the channel, set tags to an empty array.

However that does not work at all, as the API returns:

{"error":"Bad Request","status":400,"message":"The request must update at least one channel property field."}

When receiving the following payload:

{"tags": []}


If you send the following the title gets updated and the tags remain untouched:

{"title": "Test ing the API", "tags": []}