Your PIN is something you created when you activate your SIM.
As noted by @JL9, you will need contact a CS_Agent to help you reset your PIN via SIMon Chatbot and create a ticket or via private message on this Community page.
You selected a 4 digit pin when you activated your account. If you've forgotten it you'll need to go to top of this page and click Get Help / Chat with Simon to start process of CSA assistance. Then watch the little envelope icon on top right side of page will be highlighted when they reply.
From help section...
My Account Setup
When you activate your account online with us, we’ll help set up a My Account for you at the same time. My Account is your one stop shop for everything Public Mobile, including making payments, checking usage, changing personal information, or updating your plan.
If you activate at one of our retail partners, you will need to create a My Account
.
After creating your username (which must be an email address), password, security question, and PIN, you should keep this information in a safe place in case you forget.
You will need your email address and password to sign in to your My Account.
Your PIN will be used when interacting with our Customer Support Agents for account support and when calling *611, which allows you to make basic account changes.
Your security question will be used to validate your identity when making account changes.
Sometimes the welcome text/email will have the PIN although that is increasingly not the case anymore. If you don't know it at all, you will have to reach out to a CSA via ticket or private message to get them to reset it for you using verification questions
