Macbook Pro asks for old iCloud password for Find My Mac
Find My Mac sends the Mac's device ID and other information to Apple's servers and links it to the iCloud account which enabled the service. Once registered, only a correct login with that iCloud account's credentials will disable it.  Wiping the disk does not change the serial number and other information which resides on silicon somewhere on the logic board, and not in NVRAM.
If you have invoices or bills of sale which prove your company owns the laptop, you can contact Apple Support and they will (eventually) unlock the laptop.
I work in elementary education, and Apple Education support has a well-honed procedure for disabling iCloud-locked laptops and iPads. Fortunately, all our purchases go through Apple, so they already have a record of our devices, purchase dates, etc.