how to delete a store in HQ

you should have transferred the inventory to wherever the merchandise went so the accounting works right, but to remove the entries from the item store quantity page, try this sql command:

delete from itemdynamic where storeid= (store number)

Reusing the store number is a bad idea, you are better off using a new number. There are many places where new data will conflict with existing info from the previous store: transaction, transactionentry, taxentry, taxtotals, tenderentry, tendertotals, timecard, timeclock, timestamplog, signaturecapture, dailysales, batch, journal, payment, voucherentry, order, orderentry, orderhistory, purchaseorder, purchaseorderentry, purchaseorderentrydetail, receipt, cashier, salesrep, physicalinventory, physicalinventoryentry, register, and probably a bunch more. You could try to delete all reference to the old store, but it is better to leave the history and make a new number, better for the accountants and auditors too.