Solutions:
A: If forget password, determine whether bind to Mi account. If it is bound, choose to forget the password and enter the Mi account password.
B: If forget the password and do not bind to Mi account, please refer to troubleshooting steps of forgetting lock screen password, Phone Unlocking Q&As.
Please follow below to solve the problem.
1. Power off mobile phone.
2. Press and hold “VOLUME +” key and POWER key to enter Recovery mode
3. Wipe data.
Note: this step will cause all data on the phone erased and the data won’t be retrieved if not backed up in advance.
4. Reboot the phone to exit Recovery Mode.