@AliTaghavi, you're very right that downvoting and removing questions without a comment is cowardly and immoral and often grossly abused.
It's interesting that the two participants that support secret down-voting are anonymous.
There is nothing about mathematics that requires secrecy. MO should be about mathematics, hence up/down voting should be about mathematics and not about other issues as true or imaginary bad manners, etc. MO administration may treat those other issues but without affecting the mathematics on MO via down-votes and/or removing a question.