menus.remove()

let removing = browser.menus.remove(
  menuItemId      // integer or string
)

function onRemoved() {
  console.log("item removed successfully");
}
function onError() {
  console.log("error removing item:", browser.runtime.lastError);
}
browser.menus.create({
  id: "remove-me",
  title: "Remove me!",
  contexts: ["all"],
});
browser.menus.onClicked.addListener((info, tab) => {
  if (info.menuItemId === "remove-me") {
    let removing = browser.menus.remove(info.menuItemId);
    removing.then(onRemoved, onError);
  }
});