When an element be optional, the suggestion SOAPUI makes may look like what you showed and seen. That feature is controlled by the Preference > WSDL tab's Include Optional select box. If the box is unselected, that optional elements might even not appear in the template request. That may spare you some effort but the disconvenience is that you might not aware that optional elements could exist and of what names... and that, from time to time, you might want them to be there with data.
Now to the question itself,
I have to leave those empty or I can remove those tags?
If you do not have data to that regard to send as request, the proper thing to do is to "remove" them. If you leave them empty, it means the data of that tag be empty
string, strictly speaking, it is not the same thing as it being removed.
Having said, some ws has a very approximative schema and that the behaviour in terms of response may very well be just the same as it being left there with empty (or even with some white spaces). This can only be qualified as a compromise between drafting a more rigorous schema and the convenience of drafting an approximative schema. That happens more often than one might think. But the proper thing to do if you mean no data at all is to remove them.
