Permalinks – history?

I’m taking over a site that was not completed. All the pages that had been created were deleted.

I created a page and tried to rename its permalink to ‘volunteer’.

However, I SUSPECT this page was once created because when I edit it and name it to /volunteer … it automatically saves it as /volunteer-2 ?

IF I create a random named page ..i.e. testingPage, it will save the permalink like that just fine.

(My permalinks setting is set to: /%postname%/) …

SO I am pretty sure there is a list somewhere of previously saved page names… can someone tell me where thats at and how I can clear it?