I'm going to ghost my best friend
Could you explain to me why you want to ghost your best friend?
He wants to date me but I just want to be friends.
That is awkward.  However, it is rude to stop talking to someone for no reason, especially your best friend.
Meh people change.
People change and that is true, but he deserves to know that you're not interested in him that way instead of just ghosting him. If he was truly your best friend, then you wouldn't want to hurt him by disappearing with no explanation-- it could take him years to get over something like that!