Yes the use of a water flosser on your teeth can remove plaque.
A water flosser can remove up to 99.9% of plaque on your teeth if you use the water flosser correctly and often enough.
You can also prevent dental plaque buildup by using a water flosser often and also using string floss and brushing your teeth 3 times per day.
A dentist can also remove severe plaque buildup that may not come off as easily at home.
I go to the dentist at least once per year and have a good dental cleaning and they remove any hard to get at plaque with ease.
It's worth the cost to me for a yearly dental cleaning as your teeth are very important and we need to keep them clean.