DELL OptiPlex GXpro

A fried ask me about a problem with his computer.
Is the first time when I touch a computer like this.
He set a system password in BIOS (he know the password and I tested it. It’s OK!) But this password didn’t let me to change something in BIOS.
Require to enter a second (or same!?) password for changes and didn’t work.
How I can reset the second password or BIOS?
Thank you.