A client generally has the right to terminate the relationship with the client's attorney, at any time with or without cause. An attorney is entitled to notice of the discharge. Although such notice need not be formal, it is preferable that the notice be in writing and signed by the client.
On the other hand, an attorney is not at liberty to terminate the relationship or to abandon a case without reasonable cause. If such cause does exist, the attorney may terminate only on giving reasonable notice to the client and usually after obtaining an order from the court in which the attorney is representing the client (if a court action is involved).