best way to remove a nut?

What's the best way to remove a nut without damaging the fretboard or neck in general? I want to replace the plastic but with a brass one I have. Also the plastic one has worn down a lot over the years and I just want to install this brass but I got given by a friend

Great choice, brass is.

Some people use hair dryers to warm the area up first but I don't. Take a razor blade and slice between the nut and wood. Go precisely so you are cutting glue and not wood. If you can't, cut plastic, not wood.

Take a screw driver and gently tap the nut upward and out. If it doesn't go with gentle taps, cut deeper into the glue. It should pop right off.

I agree, seems to give better tone to me than most other materials uses for nuts. They come standard on many guitars for a reason

I shall be giving that a go later on

generally good advice... I mix the hair dryer and razorblade methods warming the glue a bit so it is easy to get under the nut without cutting any wood. Not everyone has great vision and though I am 20/20 I really think a little warming is a good idea. Brass is a fun nut material and will really modify the guitar's frequency response in cool ways.