tabs.remove()

var removing = browser.tabs.remove(
  tabIds, // integer or integer array
);

function onRemoved() {
  console.log(`Removed`);
}
function onError(error) {
  console.log(`Error: ${error}`);
}
var removing = browser.tabs.remove(2);
removing.then(onRemoved, onError);

function onRemoved() {
  console.log(`Removed`);
}
function onError(error) {
  console.log(`Error: ${error}`);
}
var removing = browser.tabs.remove([15, 14, 1]);
removing.then(onRemoved, onError);