Let's see if I can get you to think through to an answer without just spelling it out. ;-) Think about what kind of objects you need to detect collisions with. You could collide with the side of the window, but I'm sure you've dealt with that already. The ball itself is a circle, and it's the only circle. Besides, you don't need to worry about it colliding with itself. Other objects to worry about are the bricks, the paddle, and later, the scoreboard which is a label.
So now, ask yourself what collisions you need to handle? If you hit anything other than a brick or the paddle, do you need to do anything about it? (Remember, collisions with a wall, i.e., the edge of the window are handled by position, not by detecting collision.) Do the bricks and the paddle have any traits in common? And are they the only objects like this? And if so, can you tell the paddle from a brick? (It doesn't matter which brick.)
OK, once you figure that out, then you need to be able to tell a paddle from a brick. This should be easy for you to implement. Now, consider this. Once you hit a brick, you should be able to identify the brick by retrieving the object from the detect collision function and delete it. In fact, you probably don't even need to know which brick it is in the array.
I know this answer is a little cryptic, but I wanted to guide you to the answer, not hand it over on a silver platter. ;-)