Hi Loïc,
When you want to re-run cmake you need to do it in the corresponding folder. For instance from what you said you tried to run cmake /home/loic/OTB/otb in the folder where you build the SuperBuild project. So cmake is telling you that you cannot run two different project in the same place. If you want to re-run the otb cmake (different from the superbuild one) you need to go under the following folder /home/loic/OTB/superbuild_build/OTB/build/ (with superbuild_build the folder where you build the superbuild project).
You can add the lsgrm.remote.cmake before building the superbuild if you want to avoid re-running OTB build.
I hope it helps,
Antoine