matlab 关闭指定图例

x = linspace(0,pi);
y1 = cos(x);
plot(x,y1);

hold on
y2 = cos(2*x);
plot(x,y2,'HandleVisibility','off');

y3 = cos(3*x);
plot(x,y3);
hold off
legend('First','Third')

https://blog.csdn.net/happyangry/article/details/88290687