Simply use below query:
USE <dbname>;
EXEC sp_configure 'clr enabled' ,1
GO
RECONFIGURE
GO
EXEC sp_configure 'clr enabled' -- make sure it took
GO
USE <dbname>
GO
EXEC sp_changedbowner 'sa'
USE <dbname>
GO
ALTER DATABASE <dbname> SET TRUSTWORTHY ON;
USE <dbname>;
EXEC sp_configure 'clr enabled' ,1
GO
RECONFIGURE
GO
EXEC sp_configure 'clr enabled' -- make sure it took
GO
USE <dbname>
GO
EXEC sp_changedbowner 'sa'
USE <dbname>
GO
ALTER DATABASE <dbname> SET TRUSTWORTHY ON;