Try the steps below. These steps are for the Latitude series but the Inspiron series could be similar. Do you have the model number for the laptop? So we can look up further information should the steps below fail to disable the HDD password.
1. To enter the System Setup program, press <Fn><F1> (or <Scroll Lock> <F1> on an external keyboard if the External Hot Key option is enabled in the System Setup program).
2. Press <Alt><p> to go to Page 2 of the System Setup program.
3. Use the up- or down-arrow key to highlight Disk Password.
4. Press the left- or right-arrow key once.
5. If you are setting or changing a password, type a password and then press <Enter>. If you are disabling a password, enter the current password and press <Enter> twice.
You can use up to eight characters (including spaces) in your password. The computer makes no distinction between lowercase or uppercase letters. As you enter each character, a placeholder appears in the field. To erase a character when typing your password, press <Backspace>.
6. When prompted to confirm the password, type the password again and press <Enter>.