There's no requirement to delete your free account and it would be accessible to you again if you ever decided to play again and any tokens you won will still be there.
The reason there's no delete button if to prevent players deleting their account by mistake and losing all their progress.
However, if you really want the account deleted please contact support by following these steps:
1. Click the link https://help.ea.com/en/contact-us/ask and sign in with your Pogo name and password.
2. Where it says: ’What Can We Help you With’, type in "Pogo"
3. Click Find Solutions
4. Select "Account Management" from the drop-down list
5. Click: Find Solutions
6. Scroll down a little and on the lower right hand side, Click "I Still need Help"
The Window Will Open...
Scroll down a little further, you'll see the Email button. A form will be displayed for you to use to send to support.
Hope this helps.