Can i remove the mod remove interior fog v2 from and ongoing save without anything bad happening to my save....

its conflicting with rcrn...

remove interior fog v2 : http://www.nexusmods.com/skyrim/mods/29253/?

rcrn : http://www.rcrncommunity.com/download

thanks for any help given.

Yes, it's safe to remove it. As a general rule, you should not remove scripted mods from an ongoing game, but mods like Remove Interior Fog are safe to remove.