I think you should not permanently delete those data since you have mentioned it crucial (I think you mean crucial to the user here.) for example I don't want to delete my order history in amazon for any reason, since I always want to come back and see my order history any time I want.
If user insists for that then you can show a confirmation say:
You have decided to delete this info and this will be moved to deleted history section
then move deleted information to say some deleted history tab or a section this is just an example, which can be changed according to the use-case.
the point here is most of the time user don't want any of his information to be lost, especially those which are generated by your app.
hope this helps.