Hi Olufemi,
You will need to use the Activationtool.exe to do this (Found in the link below, or from your C:\Program Files\Laserfiche\Server folder), but first you will need to request from your Laserfiche BDM the activation history so you know which ones you need to deactivate.
Generally, if you go to C:\Program Files\Laserfiche\Server\showhwfp it would show you the hardware fingerprint on that specific PC. But, because you are missing those laptops, you will need to get that detail from Laserfiche direct and they can pass to you all activations on the required key you need information on.
Once you receive them from Laserfiche, follow this link and it details exactly what you need to do:
https://support.laserfiche.com/kb/1012301/deactivating-laserfiche-products
This gives you the option to deactivate without the need of the laptop being at hand.
Thanks
Ziad