You can reset the password by booting the product into "Recovery Mode" and "Zeroize critical security parameters"
If you have Identity-based User Accounts enabled, and you still have access to an account with the Security Officer privileges, you could use this to configure new passwords on the account where the password has been lost. If you only have one Security Officer account, and that's the password you've forgotten then Recovery Mode will be the only option.
Remember that all the security parameters will be lost when you zeroize CSPs, so you'll need to restore user accounts and passwords for each account, plus AES keys, and the security certificates for HTTPS.