All the possible positions of the value 7 in four different rows are in the same four cols. Because the number of rows matches the number of cols, and because each row must contain the value 7; each col will have a 7 in one of the intersecting cells.
Hence other possible positions of the value 7 that are in the cols but not in one of the rows can be removed.
Therefore we can remove A6-7, C6-7, F7-7.