Minn. Stat. § 508.72

Any act which may legally be done or performed by any person under this chapter may be done and performed by an agent when duly authorized in writing. The instrument or power of attorney shall be filed with and registered by the registrar if it is executed and acknowledged as required by law in the case of a deed. Any instrument revoking the power of attorney may be filed and registered if it is executed and acknowledged in the same way. A written instrument of revocation of an unregistered power of attorney, executed and acknowledged by a person having a registered interest in land, may be filed for registration as a memorial upon the certificate of title.