Can't delete Plot line

Hi guys i need some help with my code. im trying to delete a plot line but mathlab doesnt let me.

if ventilst== 1
    %Weißer Hintergrund
    xbodenw1 = [-500 -500 -498 -498];
    ybodenw1 = [-115 -815 -815 -115];
    p1= plot([-9735 -375], [-875 -875], 'k');
    assignin('base','p1',p1);
    p2= evalin('base','p2');
        delete(p2)


end
if ventilst== 0
    p2= plot([9735 -375], [-875 -875], 'k');
    assignin('base','p2',p2);

    p1= evalin('base','p1');
    delete(p1)

end

Answer 1

[Walter Roberson]

You have no hold on in what you show. When hold is not on (or equivalent internal settings) then each plot() call effectively calls cla() before doing the plotting, which would have the effect of deleting the existing line.

Try

if ishandle(p2); delete(p2); end