1- Head to https://theworknumber.com/view-my-data-sign-up
2- Create an account: you must create an account and make note of your account ID (that you choose yourself). You will be asked for it.
3- If you're curious, download your report (I did, it was interesting to know what they have on me)
4- Then go here https://theworknumber.com/employee-data-freeze/
5- You have the choice of using Email, Mail, or Fax, or you can call the number: 866-222-5880
6- I chose to call 866-222-5880
7- Press 1 for English
8- You will be presented with 3 options
9- Option 3 "To report a possible identity theft" is what you want
Someone will answer your call, ask your name, phone number, email address and finally ask why you are calling. Tell them "I'd like to put a freeze on my employment data". They will ask you for a reason; just say "It's personal".
You will be asked for your account ID and other information to verify your identity (they will ask your SSN).
Finally you will receive a text message with a code. You will give this code back to your interlocutor.
They will put a freeze on your data.