You can manually remove them or spray neem oil or insecticidal soap on any affected plants, especially during the crawler stage when they are most vulnerable.  Systemic insecticides are also available and can be effective.  They are absorbed into the plant and kill feeding pests.  

Here is a detailed article about various types of scale.  It includes suggestions for treatment - https://extension.umd.edu/resource/scale-insects-indoor-plants/