Alright, this is easy. First way: Find/create and empty charset file, or at least one with an empty space, Use the event "Change Sprite Association" (first page) and tah-dah. No Guy. After the event, change him back.

Second way: Make a hero and name him "Blank" don't set any graphic for him or set an empty graphic. When you want the seen to take place, remove your main character and add him. (I advise the first way considering this works better for games with one protagonist.)