Technical need not mean IT, it can just refer to logistics...., Or you could due to logistical reasons.

"Technical" includes many possibilities such as timing, logistics, capacity, or personnel. However, "technical" does not include human or philosophical reasons. For example, if you cancel a project because you decided that it was just a plain awful idea, that does not qualify as a "technical" reason. If you don't want to specify a reason, you can say something like "Due to internal considerations, we have decided to cancel this project." ("internal" here means we would rather not talk about it) or "after deliberating on the matter, our staff has concluded it would be best not to procede with this project."

For most scenarios yes, but “ technical doesn’t cover many reasons for termination or discontinuing a project perhaps. Depending on the subject you could also say… due to unforeseen circumstances …….

Hi, yes you can use this in most context (it's like a polite way to avoid explaining what the reasons are). You can also use operational reasons in the same way.