I'm brand spanking new to Processing, but not to programming. I'm going through the examples and can't figure out a couple of things about drawing images.

1) how do I remove it after I draw it?

2) if I want to draw shapes above the image, do I need to make the image be a background?

Here's the code I'm playing with:


PImage pica;  // Declare variable "pica" of type PImage


void setup() {
 size(400, 400);
 background(192, 64, 0);
 pica = loadImage("jelly.jpg");
}


// the draw() function runs repeatedly.
void draw() {
 
 stroke(255);
 line(150, 25, mouseX, mouseY);

 if (mouseX > 100) {
   image(pica, 0, 0);
 }
 
 else {
    // how to delete the image?

  }

}


In the above example, I'd like to remove the image from the canvas when the mouseX >= 100. And if possible, I'd like to do so without affecting whatever lines have been drawn on the canvas. Currently it removes all the lines when the image is replaced.

Thanks for any help.

As said, in Processing, all drawings persist on screen, the only way to remove them is to draw over them.
Actually, the most common idiom is to erase the full sketch surface (usually with background() or by drawing an image over it) and redraw everything on each draw() call.
It supposes, if drawings come from user interaction (like a paint program), that you record everything they do. Either the coordinates of actions, or as said you draw in a secondary graphics and display it on screen, adding any secondary graphics (eg. controls) over it.