You may want to use the EIN for your business even though it is not required, because that way you don't have to give your personal SSN to customers who need you to fill out a W-9. You will also need the EIN if you hire any employees.
However, make sure you got the right kind of EIN. If you told the IRS interactive tool that you were a partnership or S-corp, and not a single-member LLC/disregarded entity, then you need to cancel that EIN and request a new one as a single member LLC/sole proprietorship/disregarded entity.
