I've created a group and a channel on Telegram, but they're no longer in use.
I can leave a group/channel, but it doesn't solve my problem.
How do I remove them completely?
I've tried Telegram Desktop v1.5.4 on Windows.
I've found it by following these steps (in Telegram Desktop v1.5.4 on Windows):
On Android app (Telegram X), the following steps should work:
Related question on Quora: How do I delete an abandoned Telegram channel?.