Call your local animal shelter and tell them why you need to get rid of him. They will help you.

 Try to work with him, train him or get him some training, spend a lot of time with him. if you cannot keep him or don't want to you should maybe put an ad in the news paper or on the net. Find him a really good home. Screen the people very well who decide to take him in. I would suggest NO KIDS, AND NO OTHER PETS, someone that has a lot of patience for a dog like this. I'm really sorry that you have to get rid of him. GOOD LUCK! And i hope you find the dog a good home.

 Aggression is a serious issue and needs to be addressed immediately.  If you do not feel that you both will be able to work with a trainer and your dog at home then he needs to be re-homed.  The problem with rehoming an aggressive dog is that he may bite others and you are responsible.

The best place for him if you cannot work with him is to find a Doberman rescue.  Rescue groups that deal with specific breeds have a lot of experience with these dogs and the negative behaviors they have.  Do not rehome him with a friend or acquaintance that does not fully understand that he is aggressive, they will need to work with him a lot, work with a trainer, and he will be a high maintenance dog.

Dropping him of at the shelter should not cost any money.  They will take him and temperament test him.  If he shows too much aggression they will deem him un-adoptable and he will be euthanized.

Discuss your issues with your veterinarian.  Your veterinarian will give you their opinion if he is an adoptable dog or if he will be a danger to others.  There are some dogs that euthanasia is the best choice.  These situations are never easy.