Make DB tables customizable from an Admin
You don't want to be in the business of constantly dynamically creating a separate table for each store's admin to store their own data in. Instead, use a single table and designate a column to differentiate the admin's customization, organized by store.

You haven't given enough details to get into the minutiae of the implementation, but this approach can facilitate having users only see/edit data from their store with a view, stored procedures, etc. once you associate each employee and inventory item to a specific store.

  Inventory
  ---------
  Image
  Description
  Price
  Store

  Employee
  ---------
  Name
  Store
  Title
  StartDate