If a bounty offered on question which does not deserve it, can moderators or other member cancel the bounty ?? Because some question will not be constructive or which can be understand only If we have enough and clear information about the problem specified. Some other people may offer the bounty on that question, in such cases can moderator or others cancel it or not??
Moderators can remove bounties, but that is done on very specific cases, and not because the question doesn't deserve it.
Moderators should not be called to judge when a question deserves a bounty. They can do something when a bounty is offered to avoid a question is closed, and that happened more than once for a question. In the other cases, moderators don't remove a bounty; an exception could be when the OP wanted to offer more for a bounty, and flags her/his question to have it removed, and re-apply it.
There is always the risk of getting answer that are not constructive, given from who tries to get the bounty, but that is not a reason for removing a bounty. If the question is really so bad, it could be closed; in that case, a moderator would first remove the bounty, and then close the question.