Yes, you can change your Skill Level, but not more than once every 30 days.
You can change it in your Player Profile. To do this follow instruction below:
1. Go to "Player Profile"
2. Scroll a little bit down and use button "Edit Profile"
3. There you need to choose button "Player"
4. Here you can change your skill level.
One more way to change your skill level is to use your profile "settings". After you press this button you'll get to the settings page of your profile. Here push button "Player" and choose your actual skill level.