Is this password in the bios or is it one for a Windows user account? Which operating system is it?
If it is in the bios, the password won't let you change bios settings.
If it is in the operating system you need the password to run the system and use programs.
To remove the password in the bios you can try clearing cmos (put a jumper across the clear cmos pins). This doesn't always work.
To remove the password in Windows you can try booting into Safe Mode by hitting F8 as you start the computer. Login as Administrator. Go to Start-->Control Panel-->User Accounts. Look up the account with the password and reset it.