You can undo the vertex creation and positioning of a Copper Area as long as you have not closed and reopened the PCB file since the last time you edited it. Once it has been closed all undo information is lost (this is true of any EasyEDA file). If you select the outline of a Copper Area, you can delete and then redraw it and reassign the desired net and other settings to it. The Editor will then automatically rebuild it for you. However redrawing a Copper Area is a pain if the outline is complicated so the simplest way is to click on the green vertices to move them, double click on them to delete them or drag a blue dot to add a new vertex. Note that you cannot delete the original vertex (the first one placed in a shape), only those created subsequently as the shape was drawn. 

Thanks Andy, Very well explained. With final checks and re-checks, I should be able to get this ordered before the weekend is up. -Cheers