contentScripts.RegisteredContentScript.unregister()

registered.unregister()

let registered = null;

async function register() {
  registered = await browser.contentScripts.register({
    matches: ["*://*.org/*"],
    js: [
      {
        code: "document.body.innerHTML = '<h1>This page has been eaten<h1>'",
      },
    ],
    runAt: "document_idle",
  });
}

function toggle() {
  if (registered) {
    registered.unregister();
    registered = null;
  } else {
    register();
  }
}

browser.browserAction.onClicked.addListener(toggle);