I want to force close my expansion panel when I clicked Update

How do I programmatically do that ?

This is what I have in my update().

update(index) {
  console.log("index", index);

  let vehicle = {};
  vehicle.VIN = this.savedVehicles[index].VIN;
  vehicle.ModelYear = this.savedVehicles[index].ModelYear;
  vehicle.Make = this.savedVehicles[index].Make;
  vehicle.Model = this.savedVehicles[index].Model;

  this.savedVehicles[index] = vehicle;
  localStorage.setItem("savedVehicles", JSON.stringify(this.savedVehicles));

  this.alert = true;
  this.alertColor = "green";
  this.alertMessage = `${vehicle.VIN} updated`;

  // hope to collapse all expansion panels