remove enclosure url from feed

You can look if your posts have any assigned enclosure meta keys, that could trigger the rss_enclosure() core function to print the <enclosure> tag. Otherwise you can try this demo plugin:

<?php
/** Plugin Name: Remove RSS Enclosure **/

add_filter( 'rss_enclosure', '__return_empty_string' );

It looks like you’ve a plugin that’s adding the <media:content> tag, e.g. via the rss2_item hook. So check your plugins. Otherwise you can try this demo plugin to remove all extra rss2 items:

<?php
/** Plugin Name: Remove All Extra rss2 Items **/

add_action( 'rss2_head', function()
{
    remove_all_actions( 'rss2_item' );
} );

We can do similar for atom– and rss feeds.

Remember to request the feed with an url cache buster when debugging.