Can i trade in my car for something cheaper?

i have an 1999 isuzu rodeo ive had it for about 2 years. No one co-signed for me and i make payments every 2 weeks. My payments are 190 dollars every two weeks!! Its this much because your credit can be ruined there and you can still buy a car. I made a big mistake is there any way i can give that to another car dealer ship for a cheaper car, i still owe like 7 thousand or so! Its just to much money. HELP PLEASE