This feature available only for desktop users.
To rename an album:-
1. Go to your Profile page from the sticky menu on the left side of the page.
OR Click on avatar, on the top right corner and choose View profile from the drop down menu.
2. Click on Photos.
3. Click on Albums.
4. Click on the album you would like to edit.
5. Click on Edit album name next to the existing name.
6. Edit the album and and click on Save.