Once you have SSN number, you should inform IRS explaining your case that you have received SSN and your in future return you will use SSN number instead ITIN. Here is the simple steps

1. Write a simple letter – addressing to IRS that you will be using SSN instead of ITIN.

2. Attach a copy of SSN (front and back pages)

3. Send the letter to Internal Revenue Service, Austin, TX 73301-0057.

Refer the Q12 for more information. https://www.irs.gov/individuals/itin-expiration-faqs