remove_query_string_param.js

const currentUrl = https://blacklane.com/?maintenance_mode=on&foo=baz

function removeQueryString(currentUrl, removeThis) {
  const url = new URL(currentUrl);
  const query_string = url.search;
  const search_params = new URLSearchParams(query_string); 

  search_params.delete(maintenance_mode);

  url.search = search_params.toString();

  return url.toString();
}

removeQueryString(currentUrl, 'maintenance_mode') // "https://blacklane.com/?foo=baz"