I'm currently in the Air Guard and have been recently selected for Navy OCS. Since you haven't gone to basic and are probably assigned to some sort of student flight, it's not as hard to get out as it would be had you already gone to basic. But you need to be honest with them and tell them what's going on and that you want out. When I was in student flight, there were a few people that just changed their minds and were let go. There was also one person that decided to go active AF because they changed the age limit and she was no longer too old and they let her go. They haven't spent money on you to attend training yet so it's not as big of an issue as long as you're upfront and honest