§1. A person cannot be removed from an office conferred for an indefinite period of time except for grave causes and according to the manner of proceeding defined by law.
§2. The same is valid for the removal of a person from an office conferred for a definite period of time before this time has elapsed, without prejudice to the prescript of can. 624, §3.
§3. A person upon whom an office is conferred at the prudent discretion of a competent authority according to the prescripts of the law can, upon the judgment of the same authority, be removed from that office for a just cause.
§4. To take effect, the decree of removal must be communicated in writing.
Source: Code of Canon Law (Vatican.va)