I meant whether it deletes itself form the admin page and doesn’t show up there anymore, but still shows up as a tag on your home page.
I think you have two problems here… one is not being to remove just that tag, and the other one being that it still shows up if you remove our plugin.
The former one I think may be a JavaScript conflict with another plugin or theme, you could try disabling other plugins and/or switching to a default WP theme temporarily and try removing that tag via the admin page to see if it works.
The latter problem will likely be caching. If you remove our plugin, the meta tag shouldn’t show since our plugin isn’t generating it anymore. You probably need to purge the cache of your site, not the cache of your browser. Depending on your caching plugin or service this can be done from different places, with W3TC you can do it in the admin bar > Performance > Purge All Caches