Delete all data for a Single Vendor in the Dabatase
Caveat: Am American that uses Microsoft SQL Server. My opinions are based on my experiences, and may need to be modified to suit your own needs.

I would maybe look at keeping the vendor_id intact, and just replace the information on that record with some filler information. In designing the database, an effort should have been made to keep the vendor information contained to only a few tables, and anywhere else that references that vendor would have been through its id field as a foreign key. This would keep the integrity of the data, especially if you have something like sales records, and really CAN'T delete a bunch of data that is vital to your own business. A vendor table could look like the below.

Vendor_id   Vendor_name   Vendor_phone
----------------------------------------
123         BigSales Co.   555-5555
234         [redacted]     [redacted]