Remove top and right axes

set(gca, 'box', 'off')

Example

subplot(1,2,1)

plot([1,4,3,6,12,15],'.-')

title('Standard plot')

subplot(1,2,2)

plot([1,4,3,6,12,15],'.-')

set(gca, 'box', 'off')

title('Top and right axes removed')

read more

http://www.mathworks.com/help/matlab/ref/axes-properties.html