Close TB and copy the Profiles folder to another location. Launch TB, Help/Troubleshooting, about:profiles, create a new profile, name it, Choose folder... and browse to a profile folder that is a subfolder of Profiles in the new location. Do this for each profile folder in Profiles.

http://kb.mozillazine.org/Moving_your_profile_folder_-_Thunderbird

and may the old Profiles directory be deleted from the Finder ?

Unwanted profiles should still appear in about:profiles, where they can be deleted.

OK thanks !