how to controling with the curve points count ?

hello,
i d like to know to controling with the curve points count in blender what if i want to increase this points count or decrease them ?
10 to 5 for example or 5 to 10 points for curve
thanks

assuming you are using 2.5x, on your properties panel ( which is over on the right ), click the button that looks like a curve segment, then in the ‘shape’ panel, adjust the ‘resolution’ value.

many thanks friend what i mean the count of the points of the curve as in the attach img
the points of the curve is 6 i want to make them 4 for example with out using delete selectd i need another way controlling with this count and how to add apoint to aclose curve like the image ?
thanks