1) delete.php
2) edit.php
3) editu.php
4) view_products.php
and
regex validation of phone number in file insert_product.php

1)editcat.php
2)deletecat.php
3)editcatu.php
4)and i have edited view_categories.php

Now you can delete and edit in View Categories option

Files Altered :
1) view_customers

Files Created :
1) deletecust.php
2) editcust.php
3) editcustu.php

 1) Insert Brand
 2) Edit Brand
 3) Delete Brand

 4) Insert Category
 5) Edit Brand
 6) Delete Brand

 7) Edit Customer Info
 8) Delete Customer

 9) Edit Products
10) Delete Products

Functionalities till now !!!

2) Delete Orders
3) Edit button is not made because admin should not have privilege to change a customer order.