Need Help Unlocking BIOS Admin Password – OptiPlex 3000 Thin Client

Hello,

I recently purchased a used Dell OptiPlex 3000 Thin Client.

When I enter the BIOS, it shows "Admin Unlock" and asks for an administrator password. I do not have this password.

I already removed the CMOS battery, but the password remains. I need to disable Secure Boot in order to install Proxmox VE.