how to delete questions on here??

You can't Delete a Question you have asked if it has even just 1 Answer.
Answers you have given can be deleted as long as a Best Answer has not been chosen.
Switch to Desktop mode on Mobile.

Before an Answer is given click the Blue Edit Tab under the Question and then Delete.
The Delete option for your Question goes away with an Answer being given and only will show Add Update and Make Anonymous.

You can use the Make Anonymous choice so no one will know it is you if Questions or Answers are of a personal or embarrassing nature.
If you use the Anonymous option as you can do at any time,it will not show your name or avatar, and cannot be clicked to see your profile. Anonymous questions will not show to anyone on your profile page no matter what your settings are, only you will see it..

If no answers, use the edit button. If the question has answers, the only real way to remove them is as violations. You will need to get friends and network to report. The easiest thing to do is go to the question and change the asker to anonymous. You will then be the only one who knows it is you. The staff in the past would remove one or two, but no longer.

There is no way to do that. Once questions have been answered it isn't possible to delete them.