You can simply just tell him that your not interested in him and do not want to be bothered by him anymore and if he just does not want to hear it,say something along the lines of " oh it's me not you" type of thing and hopefully he will move on to someone else because he may like you if he annoys you alot, good luck and I hope I helped!
Lying sometimes backfires so be-careful! So with me I would pray about it! If you are not the praying type you could meditation on it and if you are still not into that then you need to listen to your higher self! That means looking for the answer within! You have heard a lot of answers of what to do some silly, some just terrible, some made you think! So with all these set some time alone close your eyes and see if you can gather all what you have seen so far and get the answer you seek! Remember sometimes the harder you try to push something away the harder it is!