When I was at the elementary schools, I was taught that scancellare is not correct, and that I should always say cancellare. When I grew up, I have heard that scancellare is correct, and that the initial S is, someway, an intensifier.
Is scancellare really correct/acceptable? If it is not in standard Italian, is it acceptable in some contexts? For example, could be acceptable as regionalism?
Lo Zingarelli 2013 reports scancellare, but it says it is lett. pop. (I guess it means it is literary and popular.) The application I use on my Mac links scancellare to cancellare, which means that, looking for scancellare, I get the description for cancellare with just a small reference to scancellare.
What I am asking is if it is a word I could use in a formal context, during school tests, or similar contexts.