No direct experience but I do know of several examples where whole bodies of elders have been removed & congregations have even been disbanded. Usually it happens when complete bodies of elders are in constant in-fighting or there is rampant nepotism or other problems. A special committee is formed of senior JWs (usually existing or ex-circuit overseers or long established R&F elders) to investigate and report to the Branch.
When a whole body of elders are removed , then elders from neighbouring congregations take over. The branch tries to encourage other elders to move in permanently. Usually some of the removed elders regain their position in time.
If the problems are really serious and it is viable , then the congregation is disbanded and the JWs are re-allocated amongst neighbouring congregations.
On many occasions perfectly innocent elders are removed , even some who have tried to act like peacemakers in difficult situations. This is because Special Committees generally take a "root & branch" approach and often feel it is best just to remove everybody and then brothers can try to regain their privileges. I know many elders innocently caught up in this kind of situation and it never fails to cause serious resentment.
These situations are not uncommon - I've known of several over the years.