You will need to obtain that from your seller.

If they cannot provide it, it's either return it for a refund or replace the system board.

It seems there is a jumper and 3 sets of jumper pins on motherboard below blue x16 slot.  The pin instructions are on board.  1 set of pins are for bios password clearance

https://www.hardware-corner.net/wp-content/uploads/2020/06/OptiPlex_5080SFF_motherboard-1080x866.jpg