To disable the additional content, yes. However, if you do this with a save game that's been using that dlc, you will almost certainly encounter CTD"s and other problems. There may be some bugfixes and minor improvements that were included in the dlc that aren't disabled directly, but you probably won't notice those. Also, the resources (animations, sounds, visual effects) for the additional creatures quests and such will still be in your skyrim folder, but since nothing is referencing them they have no effect (kind of like having a tool you never use).