Disabling the Mod so you can Play Other Saves
You can easily disable the mod by going to Documents/Anno117 - Pax Romana/mods/active-profile.txt and placing a # before the mods name like this:
# celtic-independence-overhaul-jtmzac
If the game was running you will need to restart it to unload the mod.
Enabling the Mod Again
Simply remove the # and restart/launch the game to enable the mod again.