Willy, that's the bad side of Recreation.gov. They don't even refund part of your money. If they did, more people would cancel and make permits available to others. I have suggested this multiple times!
As it is now, you cannot transfer your permits to anyone else -- the trip leader or alternate must show their ID to pick up the permit at the Visitor Center.
All you can do is go online, and cancel your reservation, so someone else can pick it up. Your slots would show up online at a random time in the 24 hours following the time you canceled. If you can do that, you will be helping other hikers looking for a permit.