P5 serial port not closing

I am using p5 serial library, everything works fine but the only thing is I am unable to close the port once done using it. The browser once opened will not close the port so I wanted to use keypressed() function to close the port when ESCAPE key is pressed. But it is not working. I get the message in console that it is close but it is not closed(another terminal says port is busy). In order to close I had to use the p5 serial port monitor.

The following is the code:

let serial;
var pot;

function setup() {
  createCanvas(400, 400);
  serial = new p5.SerialPort();
   serial.on('data', portData);
   serial.on('close', portClose); 

function draw(){
  ellipse(width/2, height/2, pot, pot);

function portData() {
  pot = Number(serial.readLine());

function portClose(){
    print("Serial Port is Closed");

function keyPressed() {
  if (keyCode === ESCAPE) {

how can I close the port with key pressed or button would be helpful.