drush field-delete deleted_date_N --bundle=content_type

function hottopicsnotify_update_7002() {
  // Clear cache first?

  field_delete_field('field_effect');

  field_purge_batch();
}

drush updb

public function renameTable($table, $new_name) {
if (!$this->tableExists($table)) {
  return FALSE;
//      throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));
    }
    if ($this->tableExists($new_name)) {
      return FALSE;
//      throw new DatabaseSchemaObjectExistsException(t("Cannot rename @table to @table_new: table @table_new already exists.", array('@table' => $table, '@table_new' => $new_name)));
    }