You can close your Smart ISA by heading to your Smart Savings Hub. From there, click Manage in the top right corner, then click Account information, Smart ISA details and Close my Smart ISA.

The closure process varies depending on the type of pots you have:

Access ISA pots 

You can close your Access ISA anytime without charge.

Fixed Term ISA pots 

You’ll need to break the fixed term before you can close these pots.

If you’re within the 14-day cancellation period, there’s no charge for this. But if it's been more than 14 days since you opened your Smart ISA, you'll need to pay an interest charge to end your fixed term early.