Hide Autoptimize clear cache button for users in WordPress Dashboard.

utils.php

// This style hides the autoptimize clear cache button for users in WordPress Dashboard.
add_action('admin_head', function() { ?>
  <style>
    #wp-admin-bar-autoptimize-delete-cache,
    .wp-core-ui .button-primary[name="autoptimize_cache_clean"] {
      display: none;
    }
  </style>
<?php }, 10, 1);