Stop WordPress automatically showing <p></p> tags

You need to run the remove_filter function in the after_setup_theme hook. The reason been is that it might get overrun by later on by the content or excerpt. So you would use the function as follow

function remove_the_wpautop_function() {
    remove_filter( 'the_content', 'wpautop' );
    remove_filter( 'the_excerpt', 'wpautop' );
}

add_action( 'after_setup_theme', 'remove_the_wpautop_function' );

Wordpress Visual Editor itself create those tags for new lines.

You can try to remove the filter wpautop from the_excerpt or the_content

remove_filter( 'the_content', 'wpautop' );
// OR
remove_filter( 'the_excerpt', 'wpautop' );

Sometimes it doesn't work (Didn't work for me in the past. Not with PHP).

You can try with Javascript/jQuery, place this code after DOM loaded or before the closing </body> tag.

jQuery('p:empty').remove();

Will remove all empty <p></p> elements from all over the document.

you can try this plugin

http://wordpress.org/plugins/raw-html/

or else user this in theme's functions.php file

remove_filter( 'the_content', 'wpautop' );
remove_filter( 'the_excerpt', 'wpautop' );