Oregon Revised Statutes Domestic Relations § 108.530

Community property acquired during marriage and between July 5, 1947, and April 11, 1949, may be converted into property held as tenants in common or by entirety or as the separate property of either spouse by an agreement in writing evidencing such intent, signed by both spouses in a marriage. If the agreement affects title to real property, the agreement shall describe the property affected by the agreement, shall be executed and acknowledged in the same manner as deeds and shall be recorded in the deed records of each county in which any such real property is located.