"Still deleting site…" status - r#d

Deprecation Application programming interface Method Computer Software,  text, logo png | PNGEgg
When you permanently delete a site Google has to go through its database and delete all the associated data. For large Sites this can take a while. They store all the revisions of everything on a site, so even a site that appears small may have a lot of database records from attachments, revisions, recent site activities, list items, file cabinet entries etc. It can take a long time to delete sites like this. It can actually take a few days for it to complete.

If you are still seeing this message after a week, post your issue on the Google Sites help forum.