i guess that depends on whether they are easy to pull or not. i had 4, and they had to be removed one at a time. the first was easy, the second was harder, and the third was really horrible as in embedded in the jaw-bone. that was when i decided that i'm going to keep the fourth one forever
it really depends on how they are positioned, if they have broken through the surface or not, have turned and are sideways or god knows what.
also, if it's not so easy to pull them, you would need general anaesthesia (not just local) to get them all out at once. otherwise it would be way too stressful for you (and the doctor).
what did your doctor say? will it be easy to get them out? also, i didn't know that you can have more than 4 wisdom teeth