Find the bios hot key. It may be any one of these keys since different manufacturers like to be different than others ... Delete, ESC, F10, F12, F2, INSERT.
You have to press these keys 1 at a time to find the hot key during POST before the Windows loading screen logo appears. Once you are into the BIOS you have to carefully navigate using the controls of arrow keys etc and +/- or Page Up / Page Down and Enter key to make changes etc. All bios's are different in layout and user controls. You should find an option to set Num Lock = Off etc and then select to save your changes before you exit the bios config. Once changed and saved state, then you should be all set w/o num lock on at boot.