[Senko]

I'm just wondering is there a way to drive out a possessing spirit while leaving the object/person its possessed intact? Obviously some are a clear no e.g. Shedim/Insect spirits but can a free spirit or the like be driven out as opposed to killing or destroying what its possessing?

[Sphinx]

Banishing works.

[Marcus]

In general actually killing a spirit is very difficult, and the higher the force the spirit is the harder it is.
Defeating it in combat just means it will reform in little time.

[Stainless Steel Devil Rat]

There's also the Exorcism metamagic in SG.

[Senko]

Ah so the normal risky method of getting rid of a spirit (aside from fighting it) works even if they're possesing thanks I thought there might be a special rule/benefit it got from possessing rather than being out in the open.