Water will evaporate at temperatures below boiling. The higher the temperature, the faster water evaporates.
Dehydrators typically work at around 140 degrees Fahrenheit/60 degrees Celsius, which is hot enough to dehydrate food quickly but not hot enough to cook it. A fan blows hot air over the food, and the moisture in the food basically "sweats" out.
you can remove excess water by boiling/heating, mixing it with something that is very dry like rice, it will soak it up. It depends on why you are wanting to remove excess water.
Assuming you're...