how do i remove function from key?

How do i remove the function of a key (G for example) i want it so if i hold fn then press g it registers G instead of doing the function, Here is an example (i want to press f3 and g for a shortcut but you need to hold fn and 3 for f3 and if you hold fn and press G it will just do its function meaning i cant do the shortcut ) how to i disable the function of it and any other keys? huntsman mini keyboard