Remove "Save draft" button without using CSS

You cannot just remove the "Save draft" as the button is tied up in the submitdiv metabox HTML defined in the function post_submit_meta_box().

However we can alter the callback for this metabox and replace it with our own function.

We can bind to the submitpost_box event and give the binding a height weight so it fires last...

add_action('submitpost_box', 'my_module_edit_form_after_editor', 100);

Then when our action is called we can swap out the metabox callback:

function my_module_edit_form_after_editor() {
    global $wp_meta_boxes;

    $post_type = 'feed';
    $context   = 'side';
    $priority  = 'core';

    $wp_meta_boxes[$post_type][$context][$priority]['submitdiv']['callback'] = 'my_custom_post_submit_meta_box';

}

And then we just need to define what our custom metabox will look like. You could just take the core function post_submit_meta_box() and put it into your own plugin removing the unneeded sections, however I would recommend using an actual template and not just closing php tags half way though a function as that just leads to difficult to follow horrible spaghetti code.

Please put the below lines in your wp-config.php

define('WP_POST_REVISIONS', 'false');