What are you trying to do?. I don't understand...

What I suggest is to delete the peer information for the old name before add the new client resource.

I have a client whose FQN changed. And so any time I try to add the new FQN it says the alias already exist in Networker . So, I have to wait remove the alias and wait 15 minutes before I add the new FQN. Is there way to speed up the process?

There is normally  a delay of 15 minutes before I can add the new client resource. Is there a way to speed up the process?

TRF? Is that a command?

I believe in some versions you can control DNS cache of NW... or at least I have seen it in some release notes.  I assume without that, quickest way is to bounce NW.