Membership: I want to recover a URL previously used y Protected Conent

I had both Membership and Protected Content installed. I have since removed Protected Content.

Protected Content used MYURL.com/register
Membership used MYURL.com/register-2

I deleted the "Register" page associated with Protected Content and cleared it from the bin

I'm trying to edit the permalink for Membership's registration page to:
MYURL.com/register

When you browse to MYURL.com/register it redirects to MYURL.com/register-2/

How can I get the URL to stay MYURL.com/register

?

Thank you in advance!