can i cancel a temporary car registration?

[crushedcreation]

i was buying a car from a private dealer, come to find out once i paid he still wouldn't give me the car or transfer the title. he made a temporary tag with registration in my name because he said i would feel safe that the car was mine (which is still wasn't). long story short, days past and no car. when i went to the dealer to pick up the car finally, the car was having mechanical problems. i canceled my payment for the car, lost my deposit and left the car with the dealer. he now wont cancel the registration because the car is not in good shape anymore-who knows what was done when he was keeping the car from me- he keeps telling me i own the car but the title wasn't transferred or the insurance. only registration. he says he will have the car towed and i will be charged for leaving my car on his lot. how is this possible? will i be able to cancel the registration?
oh and i'm in florida. i know the laws could differ in other states.