No, that's not possible. You can change display name but not login name. though for what it's worth, no one but a moderator or admin can see your login name (and we can see it only if we bother to look), so it's essentially irrelevant to everyone but you.
You become a sheriff by showing the skills that are needed, and no inclination to actually want to become one.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus