Remove or hide the submit button on search block in Drupal 7
One of the standard ways to do this would be to use hook_form_alter() and add the attributes to the actions element directly:

function MYMODULE_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'search_block_form') {
    $form['actions']['#attributes']['class'][] = 'element-invisible';
  }
}