The Episcopal Majority has published a paper by the Revd Canon Robert J Brooks which is titled Who Can Expel the Episcopal Church from the Anglican Communion?
Lisa Fox writes in the Preamble there:
Much virtual and real ink has been spilled about what the Episcopal Church’s constitution does or does not allow. Canon Brooks shifts the focus to the Anglican Consultative Council [ACC], which has a written constitution, unanimously adopted by the provinces of the Anglican Communion. Given that the proposed new structures have Communion-wide ramifications, it makes sense to consider what the constitution of the ACC does and does not allow.
Canon Brooks concludes that only the ACC can expel the Episcopal Church, and it would require a constitutional amendment ratified by the General Synods of two-thirds of the provinces. In other words, 26 of the synods in Anglican Communion provinces would have to vote to expel the Episcopal Church.