Yoga Sutras 2.26
Patanjali, explained by Swami Vivekananda
विवेकख्यातिरविप्लवा हानोपायः ॥
vivekakhyātiraviplavā hānopāyaḥ
The means of destruction of ignorance is unbroken practice of discrimination.
In plain words: Ignorance is removed by constantly practicing discrimination, which means always telling apart what is real from what is not. It means knowing that the true Self is not the body or mind and never changes.
Swami Vivekananda explains
This is the real goal of practice — discrimination between the real and the unreal, knowing that the Purusha is not nature, that it is neither matter nor mind, and that because it is not nature, it cannot possibly change. It is only nature which changes, combining and re-combining, dissolving continually. When through constant practice we begin to discriminate, ignorance will vanish, and the Purusha will begin to shine in its real nature — omniscient, omnipotent, omnipresent.