Do not try to drive away the unimportant and irrelevant thoughts. The more you try, the more they will return and the more strength they will gain. You will only tax your energy and will.
Become indifferent. Fill the mind with Divine thoughts and the others will gradually vanish.
There are three doshas or defects in the mind:
viz., malam, vikshepa and avarana. The impurities of the mind such as kama, krodha, lobha, moha, mada, matsarya are termed malam. This is re moved by the practice of yama, niyama and nishkama karma yoga. Vikshepa is tossing of the mind. It is removed by upasana, trataka, yoga and prana yama. Avarana is the veil of ignorance. This is removed by the study of vedantic literature, meditation and jnana.
If you entertain thoughts of hatred, you are really a murderer of that man against whom you foster such thoughts. You are committing suicide, because those thoughts rebound upon only you. Hatred ceases only by love and not by hatred. Your thoughts, sentiments, moods and emotions produce their strong impressions on the face. The face is like an advertisement board wherein is specified what is going in the mind.