I want to spite my brother and cut my beard.
Why do you want to spite your brother?
He told me to trim it and he is jealous he doesn't look as good as me.
It is ok to trim your beard if you want to. It is silly to do things other people suggest to prove a point against them.
My brother has told me to apply deodorant and to trim my beard before. I don't care.
Your brother seems like he just wants you to look fresh and clean. Still, it is your body and you are allowed to groom it as you please. Give him some hints that you want to shave your beard the way you like and he might stop his suggestions.