Yes, you will need to get rid of 2 males or get at least 8 more females that are the same age or older than yours. Pekin drakes are typically very aggressive when it comes to mating. This will start pretty quickly. You will also have the males starting to fight as they will each want to be the one that breeds with the female. You can try seperating 2 of the males but unless you have a very large area, it may or may not work. Drake flocks need to be kept out of sight of females.
I had a bad ratio of runners when I first started with ducks. 3 females, 4 males. The females were overbred to the point of being bloody and having no feathers on the back of their necks. I probably would have lost one if I wasn't around as the boys would gang up on one female and one would try to mate with her while the others were holding her down by the neck.
Also, I see in your avatar that at least one is crested. If you want to have ducklings this can be a problem. Whoever you choose to keep, if your female is crested don't keep a male that is crested. If you don't want to hatch ducklings, keep your favorite male.