Certified GKH Gardening Expert
You don't say if it's planted in the ground or in a pot. If in a pot you can move it to a shadier area and that should cut back the blooming. If you are fertilizing regularly you can cut back on that, too.
You can shear off the outer tips of foliage where the bracts and flowers form. But that may be as much or more work for clean up than the flower drop, and it may encourage more stems and more flowers/bracts.
Consider accepting the nuisance and just leaving the leaf/bract/flower litter as beneficial mulch on the soil surface to help retain soil moisture, suppress weeds and add to soil fertility.