If the cases were dismissed, then there is no conviction. There is no need to expunge because there is nothing to expunge. Your record will show "arrested" and dismissed. You can't erase the fact that you were arrested. What matters is whether you were convicted or not.
I am not sure what you mean by deferred action for childhood arrival. Please explain.
Since you were not convicted the will not make you in eligible for DACA. Consult with a competent immigration attorney. It could not hurt to expunge the arrest if your state will allow you.
First I would confirm the cases were dismissed. Once confirmed if you meet the rest of the criteria for DACA you should not have a problem.
This advice does not create an attorney client relationship and should only be used for informational purposes.
You should request your criminal records from the state and then speak to a qualified immigration attorney who specializes in Deferred Action such as myself or any one of my several colleagues.
Best of luck,
Sanjay A. Paul, Esq.
This is not legal advice. No attorney client relationship exists between us.