This is an example of enzymatic allosteric regulation. Allosteric regulation is characterised by the binding of an inhibitor to the enzyme by another location in it different from the binding active site. Allosteric has its origin from the Greek meaning: another space.
This can also be considered an example of negative feedback. As glucose 6-phosphate increases in quantity, more hexokinases are inhibited stopping the reaction that produces more glucose 6-phosphate.