I know this thread is over a year old but I'll post in case someone else runs into this problem.
I've run into the need to know how to remove TDE. In doing my research I came across this thread and some other links with similar issues. The blogs say that setting encryption to off isn't enough. You also need to drop the database encryption key. Only after performing these two steps can you create a fresh backup of the database and restore it to a new server without encryption.
USE MASTER
GO
ALTER DATABASE DBNAME
SET ENCRYPTION OFF
GO
USE DBNAME
GO
DROP DATABASE ENCRYPTION KEY
GO
reference this link: