Dynamic lighting reset "explored" areas

I'm looking for a "reset explored areas" button of some sort. All the threads ive seen seem to be referencing a button that no longer exists, since the posts are generally very old.  I must have done some testing of the map and some of the sections revealed areas do not match my current blocking shapes, so I'd like to just reset the whole map to "unexplored" but I cant find any method of doing that in the current Jumpstart UI like I was formerly able to do. If such a button or method exists, I'd like some help finding it. If it has been removed, I sure would like it back. Thanks

Hi Mark L,  The control for that is in the Dynamic Lighting button on the sidebar. It is under the on/off control for Explorer Mode. Make sure you scroll down so you can see the bottom section of Dynamic Lighting controls.

Oh, thank you so much. didnt even see that the menu could be scrolled. I tried to click and drag the box to expand it but it just looked like there wasnt any more to the menu. 

And it worked exactly like I was hoping. Excellent.