How to delete the plugin without causing seo harm

In this page these steps are described https://www.gulshankumar.net/remove-amp/

Deactivate and Delete AMP plugin.
Install and activate AMP for WP plugin (This will make process easier)
Go to Advanced Settings of AMP for WP
Enable “Change End Point to ?amp” to restore AMP official plugin permalink structure.
Again in advanced settings, do you see text area for Enter HTML in Head ? Enter below code.
<meta name="robots" content="noindex,follow"/>
Last, scroll page down till last, enable “Dev Mode in AMP“.
Keep this status for 7 days until all AMP pages are gone from SERPs.

Is there a way without installing the other plugin

If you used the most recent AMP plugin version with the ?amp=1 paired URL structure, there should be no need to do anything because accessing any URL on a WordPress site with ?amp=1 will then just be ignored. It won’t cause a 404.

The amphtml link will be removed when you deactivate the plugin.

See also https://developers.google.com/search/docs/guides/remove-amp

Thanks. Would the search engine visitor see error pages with this method ?

I have another query – i am ok with the amp pages now – but as a non technical person maintaining a website without a developer is it easy to maintain amp pages without errors in the future. My amp is working alright as of now, but this question keeps me in a loop as to keep it or not.

Thanks. Would the search engine visitor see error pages with this method ?

No, they’ll see just the regular non-AMP page. For example, here’s a blog post that doesn’t have an AMP version: https://www.whitehouse.gov/briefing-room/presidential-actions/2021/05/20/executive-order-on-climate-related-financial-risk/

If I add ?amp=1 to the end: https://www.whitehouse.gov/briefing-room/presidential-actions/2021/05/20/executive-order-on-climate-related-financial-risk/?amp=1

Then I see the same page. The amp query parameter is not recognized so it is just ignored. This is the benefit over using /amp/ as the paired URL structure: no 404 happens when AMP is deactivated.

I have another query – i am ok with the amp pages now – but as a non technical person maintaining a website without a developer is it easy to maintain amp pages without errors in the future. My amp is working alright as of now, but this question keeps me in a loop as to keep it or not.

It’s hard to say without knowing anything about your site, but Reader mode is the safest choice if you you’re a non-technical person. If you have issues in the future, you can always open a support topic.

What would be the case with amp pages that are already on the search results – if I disable the plugin would a vistor clicking on the amp page(on the search engine page) go to the non amp page automatically

As a solution I read this somewhere – you should disable all the “Content types enabled for AMP” for one week and this will non-index the pages properly and then deactivate the plugin – is this correct?

If you’re using the /amp/ paired URL structure, then you can the following plugin to remove /amp/: https://gist.github.com/westonruter/b7eb9cc7648b9a8b94b0015c79c8702e

With that plugin active, you can deactivated the AMP plugin.

Otherwise, if you’re using the ?amp=1 endpoint there is no need for this plugin since no 404s will ensue.