Using only outbound ticket
 

I found a rt fare from ICN to SEA for about $600 I think. What problems might I have using only the outbound.

I've read not using first flight could result in cancellation

Although I have Delta frequent flyer account, I wouldn't use for fear of repercussions from Delta.

I have enough to book an award outbound on another carrier.

I'm pretty much a newbie, so thank you for your patience

There are no issues with ditching the return portion as long as you’re not intending on requesting a refund.

In my experience, FFP repercussions etc. tends to be related to skiplagging which is when you abandon a journey half way at a transit point.

Just to be clear, you can ditch the return portion, but you cannot ditch the outbound portion (since the return gets cancelled if you no-show the outbound)