Thanks for being a part of the community and for reaching out.
If you are referring to your balance for ShipStation Carrier Services, when you cancel your ShipStation account with any remaining balance, you will automatically receive a refund within 30 business days.
If you have a stand-alone Stamps.com account connected to ShipStation and it still has a balance, please contact Stamps.com directly to request a refund.
Call (855) 860-7867 (Hours: M-F, 6am to 6pm PT) or email shippersupport@Stamps.com.
Hopefully this helps you out,
-Erin: Your Friendly Neighborhood ShipStation Community Manager