I want to leave TMobile.... and need number transfer pin

This is easiest way to get a transfer PIN

The easiest way to get a number transfer PIN is on the T-Mobile app. If you do not have the app download it. If you do not have an online account you need to create one. If you have an online account but do not remember your password then you need to reset it. Once signed into the app click on the "more" tab, click "profile settings", click "line settings", using the drop down menu select the line you want to port-out and click "request a transfer PIN". 
 

There is no carrier that can get you a transfer PIN in a retail store.
Transfer PINs are only obtained online or on the app at any carrier.

Please note some carriers can provide you with a transfer PIN via 611 customer service but you must be the account holder no an authorized user and be able to confirm your normal 4 to 10 digit account PIN number in order to verify your identity over the phone. 
Your PIN number is something the account holder would have created themselves at the time of account activation. If you don't know your account PIN you can reset it via 611 and you must be able to receive a one-time code to the primary line. If your phone is without data, damaged, etc. and unable to receive a text then the only other option is to go to the retail location, take 2 types of non-expired United States photo ID with you, have the rep verify them and have them call RSL for you. All the in store rep needs to do is tell the support line that you need help resetting your PIN and that they checked your IDs. The support line will not want to speak to retail representative as your account PIN is your personal information so the rep will just hand the phone back to you once they are done.