1.
If you smash something up , you completely destroy it by hitting it and breaking it into many pieces.
She took revenge on her ex-boyfriend by smashing up his home...
You could smash the drawer up with a hammer...
PHRASAL VERB : V P n (not pron) , V n P
2.
If you smash up your car, you damage it by crashing it into something.
All you told me was that he’d smashed up yet another car.
PHRASAL VERB : V P n (not pron)