Setting certain edges of a graph a different color

Can someone show me (if possible) to change a certain edge(s) of a graph to color white like the example graph below.

Answer 1

[dpb]

You mean like the following:

subplot(2,1,1)
plot(rand(10,1))
title('default -- top/bottom outlined w/ box on')
subplot(2,1,2)
plot(rand(10,1))
box off
title('no box -- top/bottom not outlined')