No, BQE CORE does not currently support voiding a vendor bill. If you need to reverse a vendor bill, you can delete it from the Accounting > Payables > Vendor Bills screen, provided it is not paid or linked to a client invoice or bill payment. Deleting a vendor bill permanently removes it from CORE.
If the bill has already been paid or is associated with an invoice, you must first void the payment (such as a check) or unlink it from the invoice before deletion. Check CORE help for details.