WHMCS, the client management system?
The OS is what loads your software, and what enables it to run. Unless WHMCS is written to be boot loaded, then no.
Think of it this way: when you boot your machine, the OS is what interfaces your hardware - disk drives, CPU, memory, keyboard, monitor, etc - to the software that is running on your machine.
In order to load WHMCS to run, you need the OS to interpret how to load, how to access the hard drive, how to access the CPU, how to access memory, how to accept input from the keyboard, etc. You need "something" to interface this for you.
This is sort of like wanting to surf the internet without being on a network. Even a cell uses a network, and the network "provides the interface" for data to be sent back and forth to your browser.
I apologize if I misunderstood the question.
