The guest user can be disabled and should be in most instances. Although to be on the safe side ensure no application requires it. The distributor_admin is the account used by replication stored procedures. This account is required if the database is involved in replication:
http://msdn.microsoft.com/en-us/library/ms151735.aspx The Administrator account depends on your environment. It would depend on the type of account it is (SQL Login, Windows login, or Windows group). This should be confirmed with whoever (developer, DBA, etc) works with that database whether it is needed or not. I would try to confirm with whoever uses the database as to whether the Administrator account is used or not. If no one can tell you then I would take note of the date and time you disable or remove the permission. Be sure to script out the account so in the event someone actually needs it you can restore the account as it was configured.