The 2010 "Shepherding the Flock " book says (these are extracts from chapt 9)
"Whereas disfellowshipping is an action taken by a judicial committee against an unrepentant wrongdoer, disassociation is an action taken by an individual who no longer desires to be one of Jehovah's Witnesses.
Actions that may indicate disassociation include the following :
Making known a firm decision to be known no longer as one of Jehovah's Witnesses.
Joining another religious organization and making known his intention to remain with it.
Willingly and unrepentantIy taking blood
Taking a course contrary to the neutral position of the Christian congregation."
Reading it carefully, there is no specific requirement to inform the subject. In theory, he has already left and gone......
In respect of blood transfusion it says
"if the elders on the committee determine that he is unrepentant, they should announce his disassociation"