why we have to divide r! for one time rather than many time?

I want clear my vague mind about combination.
Let’s say find the combinations of (A,B,C,D,E,F) persons for $4$ chairs.

Now the main thing is if you have to eliminate those over counting situations, you have to divide the permutation with $4!$. Which means:

$frac{6P4}{4!}$

My question is why $4!$ for one time.Shouldn’t it be every time when you take $4$ things out of $6$ I mean (A,B,C,D)/$4!$ then (C,D,E,F)/$4!$……….. and it goes on and on.

Please clear my mind within simple words.