Battery is common assault. You can withdraw your complaint if you wish, but it will require a visit to the police station and a statement. However if it has already been to court, you may be required to attend and explain why you want to drop the complaint.
As well as this hassle to yourself, you will annoy several police officers who have given a lot of time to you to make sure a procecution goes ahead, not including court time and the ammount of public money spent on the case.
And on a last note, if he's done it once, he'll probably do it again. Be very, very careful.