They are not showing on the widgets menu
The widgets and the layout of your particular page doesn’t seem to be produced by the theme. I suspect they came from a plugin that you are using. You’d have better luck asking the plugin author on how to disable those widgets.
As for the “Leave a Reply”, that means that the particular post (looks like a custom post from a plugin) accepts comments which can easily be disabled.
Note: For normal widgets, you can always use Widget Logic to control where the widgets will appear.