エラーが発生しました: 非表示の設定を変更することはできません: rss_polling_enabled

I think this setting may be hidden on hosted sites. I’m getting the same issue when I try and disable the plugin on a hosted site on the Business Plan:

If you’re also hosted by Discourse/CDCK then I think in this case you would need to contact team@discourse.org to enable/disable the plugin:

「いいね!」 1