Classifieds - trying to use /classifieds/ slug but can't

WP 3.5.2 subdomain multisite network

I had activated Classifieds plugin and then deactivated it

I want to use a standard page - Classifieds with the slug /classifieds/ -- but I can't. I created a page and WP auto generated /classifieds-2/ -- but there isn't a /classifieds/ slug in database posts table, so I edited /classifieds-2/ to /classifieds/ and saved it, but the page forwards to the site home page instead of to the newly created page

is the slug in some other table somewhere that I can edit/delete?

I tried searching the DB but nothing looked obvious. I actually deleted the classifieds plugin and it still redirects to main page.

I want classifieds plugin on other subsites, and '/classifieds/' pages on some sites so need this resolved.