There is a modern idea of working with Elementals and Servitors which states that once they have completed their task they should “return to the source”. In other words, they go back to where they came from. This is basically saying that once they are done, they dismantle or dissolve and allow their energies to go back to the Element or the Magician that they were created from.
In some schools of thought, and I am thinking of the older ones such as Kabbalah, and Elemental does not do this. Once it is created, it exists and remains as such. To tell it to return to source is like asking a child to return to its mother’s womb (and I don’t think the mother would appreciate that). In this case the Elemental will eventually dissolve, allowing its energy to disperse and so it will, in effect, “return to source”, but it is not an instruction that we give it, it is a natural process. An Elemental is constructed of energy and remains an energetic body, much like the Nefesh of a living person. Once the task of the Elemental has been completed, the Magician would normally stop working with said Elemental and so it would not be fed further energy from the Magician or whatever source of energy was set up for it, and because of this it would not be able to hold itself together any more. In the case of a person that dies, the Nefesh will hang around for a while, but as long as it is not being fed energy, it will dissolve and return to the Source. In the past I have also referred to this as the Phantasm, the energy that is left behind which is the Ego, that part of the soul that retains memory. It is that which people channel and speak to, the ghost that walks the halls, appearing as it did when a living person, as it retains the memory of what it once was as a solid physical body.
In the case of an Elemental that was created to protect someone, and once that task was completed, it did not “return to source”, but in fact attached itself to the husband of the woman who it was to protect for that period of time, then it has simply continued its task. The protection may have been for something specific at that time, but the task of the Elemental was to protect. Once the husband came along, the Elemental attached to him in order to keep her protected through the husband. You can’t be upset with the Elemental for not following your instructions, because to the Elemental, it is following them, i.e. protecting the person, all it did was transfer itself to the physical body who would then continue that protection and therefore be able to continue with its job. Of course I don’t know all the small details of this particular case, but am using it as an example of what can happen when you give an Elemental an instruction to do something and it doesn’t go exactly as you planned.
So to conclude this short diatribe, when creating an Elemental or Servitor, I don’t believe it necessary to give it instructions of what to do once it has finished its task. Just let it be and allow it to move back to the Source in its own way and time, just like we do.