I’m not sure I understand your issue. In WP Admin, you should be able to see the More tag within the post editing screen (both in Visual and HTML mode). You shouldn’t be seeing the tag in the sites’ frontend, the more tag is designed to limit the amount of content displayed through use of the_excerpt(). On a full post viewing (on the individual post page, or if the whole article is meant to be displayed) you won’t see the More tag or any reference to it.
If this is still an issue, please elaborate and provide direct URL’s to the problem. The clearer you can make the issue for us to see, the higher the chance we can offer a prompt resolution.