|index||This index of the grid to destroy.|
This function will remove the given grid data-structure from
memory, freeing up the resources it was using and removing all
values that it contained. This function should always be used when
you are finished using the ds_grid to prevent memory leaks that can
slow down and crash your game.
if lives = 0
The above code will check the value of the built in global variable "lives" and if it is 0, it destroys the ds_grid indexed in the variable "Wall_Grid" and then changes rooms.