Hello, i'm populating my custom world, but the game keeps generating uninteresting townies.
How do i delete them using Nraas?
Can you add your own skilled townies to the world and set them as cashier/bartender/DJ/pianist..ect..?

I suggest that you post on NRAAS' official website. You may get an answer here, but you're more likely to get an in-depth answer over there. Just keep in mind you have to get an account.

But I bet you can set specific Sims into a role using NRAAS Register. For deleting individual Sims, there's the Total Annihilation function with MasterController when you select a particular Sim.

thank you

^ I wouldn't use that method, seems a bit quick and dirty for my liking. A bit too easy. The Nraas method should be sound though.
Personally, I just keep all sims that are generated. At some point you will find that you need something like a town mechanic, a sex symbol or maybe a magician. Just take your unwanted sims into CAS and turn them into the desired sim. No need to delete. In 5 years I've never deleted a sim, theres always a role they can be made to play.

I believe that's not a safe method to delete a townie.

Here are some suggestions for Population and Town Management . Please register over at NRaas and post in Chatterbox if you have questions on how to use the mods.