The trick is not to remove what you don't need, but to only plot what you do need! What you need to create are some X,Y pairs that are on your arc, and then plot them as a series of X,Y points.
Let's assume that the center of the circle is the origin (0, 0). If it is not, simply add the X, Y coordinates of the center to all of the points we are going to calculate. Let's also assume the initial angle to the first point is 0 (it is on the X axis), and the final angle is A (again, can add values to "adjust" these assumptions). Suppose you want N points on the arc. Compute the following X-Y pairs (use a For loop): cos (Ai/N), sin(Ai/N) where i is the index of the For loop. When you plot these, you'll have an arc of unit radius. [Multiply these values by the desired radius R].
