Maybe. But others will be created (or made simpler), to wit: a teenager can now rent a google car (since he isn't driving it won't cost much more than an adult) which will enable him to do things like wash peoples windows (which is neither technically difficult nor especially dangerous) thus driving down the cost per window washing, enabling more people to enjoy this luxury.

Or, assuming you are right and delivery men are unemployed in great numbers which I agree is likely, then (as transportation prices plummet) there will be more jobs for packaging. Imagine that instead of having to collect your kids in day care, go shopping and the go home and cook you can instead preorder your groceries, have your Google Car pick up your kids, spend the time talking with them in the car, go to the shop and pick up your package (which will take 10 minutes at most, since you have likely already been charged when you made the order) and then home to cook, which kids you actually get to talk to and who are now a lot less stressed.

Even then self-driving cars will also create other oppertunities, because there is no reason the car has to stay in the lot until you get home. It might as well drive to the nearby car cleaner (which can be out-of the way since the time is essentially free, although the gas used is not) for a cleaning. That is more business (and it is low skilled) and better, nicer cars.