There is a box No vote at all/my vote to none in the ballot paper. a voters can cast vote in that column if s/he does not want to vote any candidate or political party. A voter is considered to have taken part in election even if the vote is rejected. That means the voter has not boycotted the election. And such vote is counted to none of the candidate. Such system is practiced in India, Bangladesh, Greece, Spain, Columbia as well as some states of the USA.
In the context of Nepal, In my opinion such provision should be kept in Nepal as well. there are a number of leaders who show very big dreams to the voters during the election but never remember their voters after they win the election. If None of the candidates seems to be good in voters eyes, who should they have to be choose? They may get confused. They would like to take part in the election but would like choose none of the candidates. In such situation, the voters may find this provision as their best opinion.That's why this provision should be introduced even in Nepal.