Error Invalid or deleted object while creating a line

I created a dot that is moving through the figure after this function bellow is called; I get an error invalid or deleted object after I close a figure. Also, I can't manage to figure out how to delete a customer dot after button is clicked again. I attached another function showing the button clicked called pushStart. Please help me!

function customerMoving(a)
        customerVel = [ -1, 0];
        customerPos = [90,45];
        customer = line(customerPos(1), customerPos(2),'marker','.','markersize',50,'color',[.8 .6 .6]);

        tic;
        customerWaiting = false;
        while toc < 20
             if customerPos(1) < 42 && customerVel(1) == -1
                customerVel(1) = 0;
                customerVel(2) = 1;
             end
             if customerPos(2) > 71
                customerVel(1) = -1;
                customerVel(2) = 0;
             end
             if customerPos(1) < 34 && customerVel(1) == -1
                customerVel(1) = 0;
                customerVel(2) = -1;
             end
             if customerPos(2) < 18 && customerVel(2) == -1
                customerVel(1) = 0;
                customerVel(2) = 0;
                customerWaiting = true;
                pause(0.5);
             end
             if customerWaiting == true
                 if customerPos(1) < 34
                     customerVel(1) = -1;
                     customerVel(2) = 0;
                 end
                 if customerPos(1) < 28
                    customerVel(1) = 0; 
                    customerVel(2) = 1;
                 end
                 if customerPos(2) > 26
                     customerVel(1) = -1; 
                     customerVel(2) = 0;
                 end
                 if customerPos(1) < 22
                     customerVel(1) = 0; 
                     customerVel(2) = 0;
                 end
             end

                customerPos = customerPos + customerVel;
                if a == true
                    set(customer, 'XData',customerPos(1),'YData',customerPos(2));
                     
                else
                    set(customer, 'XData',0,'YData',0); % ???????????? NEED TO REMOVE ALL THE CUSTOMERS ?????????
                     
                end
                pause(0.05);
        end
end

function pushStart (hObject, event, handles)
    global dayStart;
    if dayStart == false
        set(hObject, 'String', 'Close');
        dayStart = true;
        customerMoving(true);
    else
        set(hObject, 'String', 'Start Day');
        dayStart = false;
         customerMoving(false);
    end
end

Answer 1

[Image Analyst]

When you create a line object and get the handle of the line graphic into "customer" if you want to "NEED TO REMOVE ALL THE CUSTOMERS" then delete the line handle with delete:

customer = line(customerPos(1), customerPos(2),'marker','.','markersize',50,'color',[.8 .6 .6]);
drawnow; % Force immediate update so we can see the line.
% More code....
% Delete the line from the graph:
delete(customer);
drawnow;

[Paulius Kazemekaitis]

How do I do it in a function? Like how do I assign that created object? Because right now if I click start it runs that customer, if I click "Close" it stops it, but doesn't erase it, because I call function again and it doesn't know what prev customer, it creates the new one and deletes it straight away. This is also a problem for me then I want to get a multiple customers. I know Ill do it with for loop, but how can a program know exactly which customer is which?

[Image Analyst]

You could keep the customers in a global variable or a persistent variable.

[Paulius Kazemekaitis]

I tried as a global variable in the pushStart function, still no luck... :(

[Paulius Kazemekaitis]

Would you mind checking it if Ill send you all the files?

[Paulius Kazemekaitis]

Basically what happens is that I am doing tic; while toc < 20...

so when I am trying to delete it, I have to wait till it counts 20s. How can I make it so it will happen straight away after I click it?