In case of stack deletion of any item from stack is called pop. In any item is delete from top of the stack, When you delete any item from stack top will be decreased by 1.

 
void pop()
{
int item;
if(top==0)
{
printf("\nStack is empty: ");
}
else
{
s.item=s.stack[top];
top=top-1;
printf("deleted data is: %d",s.item);
}
}