ok, so what I got from all above thread is:
1. I have united airlines round trip ticket to travel within 2 different states/cities in USA.
2. I will use outward (my home city to other city) ticket
3. I won't use return (from other city to my home city) ticket. and this won't result in *any* additional cost to me.
Also I don't need to inform airline about not travelling back on that ticket...instead just don't show up.
Thank You for your HELP!