Cut the two small female flowers off before the flowers open. These female flowers are located on either side of the center (larger) male flower. Leave the center (larger) male flower. Do this early before the buds open, as soon as the 3 pedicels are big enough that you can safely get the clippers in there and cut the female flowers without accidently severing the male flower in the process.

Why do you have to do that?

Why do you have to do that?

It promotes vigour in the 'real' flower.
Those little pseudo flowers sap the energy and are best removed if you want big showy flowers.
Its similar to disbudding in Chrysanthemums.