When you love a person very deeply, it is always difficult to drive him out of your memory. There is no point in remembering a person who has never made you feel loved. However, I know this sounds very theoretical. The best way to keep him out of your thought is, stop struggling to drive him out. Let him be there in your memory and time will do rest of the things. Only thing you really need to do is, never ever establish any kind of communication with him by any ways. Keep your love in corner of your heart and go ahead in life. Try to convince yourself that he never deserved your love and never meant for you. Do not keep on asking yourself that why you love him so deeply because you will never find an answer to it. It just happens without any reasons. The day you will realize this, is the day he will start fading from your memory.