l want function about delete a book from this variables and structure that appear in picture to complete the bookshop system

and also what the condition and statement in case 6

case 6: / Delete a book if (lemptyArray()) lladd function here break; //Global variables declaration const int SIZE =20;// global constat int count=0; / actual array size / /Structures declaration struct Date \{ int day; int month; int year; \}; /lend of struct Date struct Book 36{ int id; string bookTitle; string author; int numofCopies; Date publishDate; \}BookArr[SIZE]; //global array of struct Book //Functions prototypes int menu(); void add_book (); bool emptyArray (); void show_allBooks (); void buy_book(); void search_ByID()