How can I become a software developer who only designs?

A young programmer asked me, "How can I become a software developer who only designs the whole software architecture and gives instructions to other developers rather than actually coding by myself?"
I told him he could do that right away, as long as he didn’t care if the other developers listened to his instructions and followed them. And if he didn't care of he was paid.
In general, software developers will not follow the lead of someone for whose designs they have no respect. And why would they respect your designs unless you had previously proved yourself by what you’ve built?
So, build things, and build more things, until you demonstrate that others have some reason to follow your lead.

And, at the same time, work on your people skills, because even if you’re the greatest designer in the world, if you’re a self-centered jerk, nobody will follow you or your designs.
For more on designing, see
System Design Heuristics