Correct, you can simply deactivate the plugin. You may see Analytics references with AMP endpoints (?amp) although these will eventually no longer occur. For example after 1 week with the AMP plugin deactivated if you check your Analytics 7 day report there should be no AMP URL references.
I see that traffic has halved. Could it be that the analitycs code is not on the AMP page?
I don’t have your URL so I can’t check your site. If however you’re using Google Analytics then you can use the Site Kit plugin, which inserts your preferred Google Analytics property on both your canonical and AMP URLs, linking both correctly. For other analytics providers your can check your amp-analytics configurations by reviewing your AMP URLs.