Help with C# - destroy at a certain position not working

Hello. Im very new to programing so still have a lot to learn. But have been learning through reading the documentation, youtube tutorials and these forums.

I have a simple game where stuff f.e. cubes randomly spawn and go twards the player. So I wanted to make a simple script to make the cubes despawn when they go behind the player (player position is Z = -100).

My Script:

public class destroyUnderZvalue : MonoBehaviour
{
	public float destroyPosition = -105.0f;

	void update()
	{
		if (transform.position.z <= destroyPosition)
		{
			Destroy (gameObject);
		}
	}
}

Tho I dont know it its <= or >= since the value is lower (-105 is lower than -100)

But when I attatch it to the cubes it does nothing. Thank you in Advance.

In “void update()” the u must be capital. Change it for “void Update()”, I’ve tested it with the changes and it’s working.