Disable "Extrude region together along the average normal" dragable UI element The yellow circle with the + icon. I pressed something accidentally on my keyboard, but I don't know what. I don't know how to get rid of it either. I suspect it has to do with the "Show Overlays" setting in the drop down above the view controls in the top-right of the view port, but I've tried all the options in there, none of them disable this circle with the +.
in the tools menu on the left side of your 3D viewport press on this icon



Or just press W to select the same tool "Select Box".