remove database ref from dm_database_encryption_keys? (SQL 2012)

The goal is to do a backup of a TDE database in Enterprise and take off encryption and thenbring a copy of standard edition.

When I ran this command
ALTER DATABASE oster
SET ENCRYPTION OFF
DROP DATABASE encryption key
and then ran this:
select * from sys.dm_database_encryption_keys  
the encryption_state status became '5', first for few minutes, and then became '1', but there was still an entry for that database in dm_database_encryption_keys .

now when i backup this new database from enterprise and restore it in standard edition, i get below:
Transparent Data Encryption is not available in the edition of this SQL Server instance. See books online for more details on feature support in different SQL Server editions.

how can we totally remove entry for that new database from dm_database_encryption_keys? maybe that is giving impression that TDE is still somewhere somehow present or
linked or alluded?

(when we create a brand new database, we dont see any entry for it in dm_database_encryption_keys). how can we bring this database to have no reference to any
entry in dm_database_encryption_keys?