As far as I know brother, there is nothing we say when we leave the toilet. Since the hadeeth which came with this Du'a is Dhaeef.
Also i remember in one of your previous posts you said that You remember that the du'a of entering the toilet and leaving the toilet are in one Hadeeth. I just want to let you know that there is a hadeeth by Anas if I'm not mistaken which only mentions the Du'a of entering the toilet.
Anas said that when Rasulullah sallallahu alaihi wa sallam used to enter the toilet he used to read "Allahumma Inni a'udhubika minal Khubthi wal khabaa'ith"
and there is no Du'a about leaving the bathroom in this Hadeeth.You can look up the book 'Umdatul Ahkaam for this hadeeth.....It's in Bab al-Khalaa' wal Istitaabah.

I dont know what Shaikh Albani said about the "Ghufraanak" hadeeth though, but as how sis amirah_87 said, one of the narrators of that hadeeth is Majhool (unknown), so that automatically makes the hadeeth Dhaeef.

Wallahu a'lam.