There are a variety of methods for clearing a super. During a heavy flow, abandoment is popular. I only do it near dark so if it fails and robbing ensues they will all go home shortely anyway. Abandonment is to remove the supers and simply pile them up in the open and wait for the bees to return to the hives. In a dearth this will cause massive robbing and is a very bad idea. Success is all in the timing. I'm too afraid of robbing so I seldom use this method.
I usually use a triangular bee escape like Brushy Mt. sells. In order to not move the supers more than once, I sometimes put the escape on a bottom board and stack the supers on top of that. usually MOST of them will clear out overnight. I brush the rest off one frame at a time.
Some people use chemicals to drive them out of the supers. I don't want chemicals in my honey, so I'm not fond of them, but Fischer's Bee Quick is the least objectionable smell (smells like benzaldehyde to me. think marichino cherries) and, although the ingredients are not listed, is claimed to be only food grade ingredients, including essential oils. This is used on some kind of fume board and the bees don't like it and leave the supers. I've never used this method.
Some people use blowers. Blowers are like bee vacs. If they are not adjusted perfectly they can kill a lot of bees by knocking them into the ground too hard. But when the are asjusted correctly, proponents say they work very well. I've never used them.
No matter what method you use there are always stragglers.