It's a non-issue. A database system uses its own filesystem inside a large file. When a row is deleted, the row is removed from the 'file' which makes up a table (semantically speaking). This could still lead to data being present on a page, but it's no longer accessable.
Removing a file with content from the windows filesystem works more or less the same. Only if you re-pave the complete harddisk byte for byte you will be safe, otherwise the tools they use at forensic labs will easily re-create your files from the disk.
So unless you re-format the piece of harddisk that's occupied with the page the row was located on, you will still have the data on disk, no matter what you do.