Suppose I ask a question, and after a long time no answer was received. Then I decide to delete my question: is this a banned behavior according to the rules of this website ?
It is not a banned behaviour, and in fact the automatic restrictions only kick in if you delete a few (to prevent deliberate vandalism, mostly)
If there were answers, especially if they had upvotes, it beomes an issue - as then a deletion will impact others.
I'd suggest though, that if the question is still of interest to you, that popping a bounty on it will gain it attention and it may get answered. This could be a better outcome.
It's not a "banned" behavior. In fact, it's advantages are of preventing vandalism, and it makes the site less cluttered.
There is a penalty for deleting questions. I believe that the penalty does not apply (or at least is lessened), if the deletion takes place more than 30 days after the question was posted. That is, "low rep" individuals who have a bunch of questions deleted before 30 days will be automatically "questioned-banned" from the site. If the questions are deleted after 30 days, the penalty is lessened or removed.
That would not apply to you, with your high rep, and as said, the stricture is less after 30 days.
There is a badge called "disciplined" for people that remove their questions from the site that are upvoted +3 or ore, and another one called "peer pressured" for removing questions downvoted -3 or worse. That's a way of the site's encouraging people to delete questions.
Another place to look (or ask) for better answers is Meta SE.