POA rows remain after removing share in Dynamics CRM -

i have removed sharing record in crm manually. not shared via cascading rule eather, remains in principal object access table. can see, script controlling growth of poa, published microsoft, deletes rows object ids er deleted crm, can't see logic removes unshared records. know if crm contains logic @ all? has had experience deleting rows despite of being unsupportet action?

thanks in advance

i can't tell how poa table populated or cleaned up, can tell how delete it:

http://dotnetdust.blogspot.com/2014/01/lessons-learned-deleting-312-million.html