How do I erase my employers tin number and keep his social security number instead ?

I believe you are asking about where you enter the federal ID number for a Form 1099-NEC. If so, click on the format that represents how the number is displayed, two numbers and a dash for an employer ID number, or three numbers and a dash for a social security number, then enter the number in the payer's federal ID Number box. To change your choice, just click on the format box again and enter the number again in the Payer's federal ID Number box.