Disfellowshipping as a Watch Tower practice extends back to Russell's day, though it has taken differing forms. Into the 1930s matters were handled by a public trial and congregation vote. This changed in the 1940s. Organizational Instructions for the Kingdom Publisher, 1945 edition says:
"If a brother sees a fellow publisher do that which is out of harmony with the Lord's organization and His instructions, he should not gossip among others; but he would do well to go to his brother and in a kind manner call his attention to his shortcomings. If an individual associated with a company persists in wrongdoing and does not act according to the Lord's Word and direction as becoming of Christians, then the representative members of the congregation who are the servants in the company, the mature ones or elders, can decide what shall be done with such person. (Deut. 21:18-21; Matt. 18:15-18) The Scriptural admonition is to have nothing to do with such an individual (Rom. 16:17; Titus 3:10) The elders would so advice the congregation (1 cor. 5:11-13) Later if genuine repentance is shown by the dismissed offender the elders may order that he be received back in their midst. - Prov. 17:10; 2 Cor. 2:6-11 7:8-12; 2 Thess. 3:14, 15."
H. H. Stroup's book should be used with care. It is full of errors and contrived material. See Schulz: Separate Identity, vol, 2 introduction where examples of Stroup's fakery are given.