Question

deleting question is considered rude behaviour; please dont do it ....

Answer 1

the questions posted belong to the community as a whole, so the we may all benefit from them; by deleting it after it is answered, you tend to be saying that you care only for yourself.

Answer 2

I agree, I refuse to help someone who delete their question

Answer 3

it may also mean that you are trying to hide something, as in getting answer on a test ... but thats a side rail

Answer 4

most likely, they want to look like they never need help.