I would like to close the hCA-i but I have balance in the account. How do I close the account?

You can close the account in the mobile app in 'Card Settings > Upsize Wallet > AmBank Account (toggle OFF)'.
The balance from the account (inclusive of accrued profit-to-date) will be transferred to your e-Wallet after the account has been closed.

Note: Do take note that you can only re-apply for the hCA-i 6 months after the account closure request date