WordPress URL Issue

On our old site, we had a page

http://www.domain.com/contact-us/

which doesnt exist anymore.

No we have http://www.domain.com/contact/

But Google tells, http://www.domain.com/contact-us/ was the famous page with good domain authority, so we tried to edit the permalink for http://www.domain.com/contact/ to contact-us , but its saving as contact-us-2

I searched for http://www.domain.com/contact-us/ on frontend and backend, but it doesnt exist, so why does it not accept contact-us ?

Is there a way to search this on database and delete the contact-us record, then it will accept ?