According to L. Ron Hubbard:
One’s body is a mass of individual thetans stuck to oneself or to the body.
One has to clean them off by running incident II and Incident I. It is a long job, requiring care, patience and good auditing. You are running beings. They respond like any preclear. Some large, some small.
Thetans believed they were one. This is the primary error. Good luck.
– from Operating Thetan Section III