Normally, no. Adept powers can only go up (so that if you start with Improved Reflexes 1, and later gain more Power Points, you can just "upgrade" to Improved Reflexes 2).
That said, if you're wanting to make a change to your character because something just isn't working out the way you thought it would, I imagine if you talk to your GM, s/he might just let you make a change. Especially as someone that's new to the game, if you thought a power worked one way, or you thought you needed X ranks in it, or you just discovered a new power you think would be cooler? Well, just chat with your GM, explain why you'd like to swap out one for another (or whatever it is you want to do), and the odds are good they should let you do so.
The first few sessions have a steep, steep, learning curve! I encourage GMs to be flexible and let folks make changes (whether you're talking Adept powers or anything else), and let players get their feet under 'em.