There is no easy or inexpensive way to remove fluoride
once it is added to municipal water.
As the fluorine element and fluoride compounds are so small you will need a high quality multi-stage reverse osmosis filtration system, one that adds the healthy nutrients back into the water, or you can add the nutrients back in manually.
If you are one of the 1% who are hypersensitive to fluorine and fluoride compounds, you will need to take into account what foods and drinks you consume as most processed consumables will have elevated levels of fluorine: you will still be absorbing fluoride by ingesting food that is grown, washed or prepared with fluoridated water.
It is possible that it absorbs through your skin when you bathe or swim in it.