split screen..how to reset to basic layout?

hi all, new to blender, and I accidentally drag out a lot of duplicated split screens which totally mess up all the layout…

it seems one can drag the little triangle with lines at the corner to duplicate the screen…but how to close it?

the whole layout out is totally messy right now, is there a way just to reset it to the basic layout?

Drag it over over the screen border either horizontally or vertically. It shows an arrow in which direction to join the screen. You can also right click on the screen border (where you normally resize) to split/join them. Note that when you join a screen, both screens have to share roughly the same border size in the direction that you want to merge them.