There are a multitude of different tap heads all of which are either a) interference fit on to the spindes which require levering off best with an adjustable spanner under the head on a cloth to prevent scratching the sink, b) screwed on to the central spindle by a small brass screw, these are often hidden under an indecies which will require a sharp small screwdriver to pry it free from the tap head, c) some old pillar taps have a small screw in the side of the 4 way head.Good luck
Chris
June 2009