you have to clear the BIOS using jumper. you'd find instructions for doing that on your board by simply googling it. usually, a jumper is a three pin switch. It has a connectore connecting two of those pins (1 and 2) jush pull it out and set it to 2 and 3.
Then when you reboot, BIOS will get into configuration screen which will have the option of clearing password (navigate a bit). Clear the password and shut down your system.