Hello friends! Sorry to bother you all with yet another probably simple question, but I've been searching and haven't quite figured out what to do.

I'm currently booked on 7/16 CO287 from EWR to Orange County. The return was scheduled for 7/19 on CO386 OC to EWR. Both were V class fares with a purchase price of $314.20.

I had something come up and needed to go (for fun, not work) the Fresno area on the 21st-23rd. So in an effort to ditch my soon to be useless NWA miles, I bought an award ticket for the r/t from EWR to Fresno. However, the ticket I got was less than appealing (think 3 flights/2 layovers in each direction).

I realized it's silly to come home from Cali on a Sun and fly back on Tuesday, then back again on Thursday. As such, I'd like to change my flights.

I'd like to keep the original outbound to Orange County and change to a return home from LAX to EWR (the 3 p.m. or so flight) on the 23rd.

Just for kicks, I priced EWR to SNA and LAX to EWR as a new reservation, and it's coming out a little less than my original r/t SNA/EWR. I went into manage my reservations and tried to change the return flight from LAX to EWR and it's coming as a $0 change, but a $150 change fee. I can ditch the NWA award ticket for no cost, so I'm not worried about that. One of my friends (who knows little about the rules, etc.) suggested that I keep my original r/t from EWR to SNA, but just ditch the last leg (SNA to EWR) and book an NWA award ticket from LAX to EWR, which, in effect would only cost me $10. I don't like to ditch a leg of a ticket and don't know if there is a penatly for doing so. What is the penalty for cancelling the entire ticket I have booked and just making a new reservation? What would be my best and least expensive option?

Thanks, as always, for your advice!