Hello, how to clear properties in app designer? Not references to variables, only meaning. In first function call, property vars dynamically changes, but in second call, there is an error that matrix dimension not equal

properties (Access = private)
      st60; % 60 milliseconds after R-edge point
      st80;% 80 milliseconds after R-edge point
      st100;% 100 milliseconds after R-edge point
      ast60;% array of st60 changes
      ast80;% array of st80 changes
      ast100;% array of st100 changes
      st60ind;
      st80ind;
      st100ind;
end

    function STAnalyse(app,r2)
            for i=1:length(r2)
            app.ast60(i) = app.ECG2(r2(i)+app.st60);
            app.ast80(i) = app.ECG2(r2(i)+app.st80);
            app.ast100(i) = app.ECG2(r2(i)+app.st100);
            app.st60ind(i) = r2(i)+app.st60;
            app.st80ind(i) = r2(i)+app.st80;
            app.st100ind(i) = r2(i)+app.st100;
            end
        end
function ClearProperties(app)
        st60=[]; % 60 milliseconds after R-edge point
        st80=[];% 80 milliseconds after R-edge point
        st100=[];% 100 milliseconds after R-edge point
        ast60=[];% array of st60 changes
        ast80=[];% array of st80 changes
        ast100=[];% array of st100 changes
        st60ind=[];
        st80ind=[];
        st100ind=[];
end