The method of changing behavior through a systematic program based on learning principles is called.

Behavior modification

Explanation:

In psychology and psychotherapy, the term Behavior modification refers to the approach used in therapy that focuses on changing undesirable/negative behaviors.

This is done by using special techniques and a systematic program by which the client identifies the problematic behaviors and develops strategies to stop them and change them to a more desirable/positive behavior. This approach has its base on the principles of classical and operant conditioning.

Therefore, the method of changing behavior  through a systematic program based on learning principles is called: behavior modification.