There are too many different conditions that can cause an ear itch. Each has its own special treatment. Seborrheic dermatitis, a condition similar to dandruff, makes ears itch. So does psoriasis. Infections, both fungal and bacterial, can drive a person to scratch the ear nonstop.
Allergies are another cause.
I know the gratification that comes from scratching an itchy ear, but scratching makes matters worse. The temporary respite that comes with a scratch is succeeded by an even more vicious itch. Many of the above conditions respond to cortisone creams, ointments and drops. Prescription cortisone products are often needed. Cortisone drugs should not be used if there is a chance of infection.