Changing the Parametization option in SQL Server 2012 from Simple to Forced
It frees the plan cache for the database that you change the option for, and nothing else.

On my server, I run these queries:

USE StackOverflow;

SELECT TOP 1000 * FROM dbo.Users AS u WHERE u.Reputation = 2;

USE StackOverflow2010;

SELECT TOP 1000 * FROM dbo.Users AS u WHERE u.Reputation = 1;


They I use sp_BlitzCache to look at my plan cache:



After that, change one database to use Forced Parameterization:

ALTER DATABASE StackOverflow SET PARAMETERIZATION FORCED


Give sp_BlitzCache another run:



Only the plan from StackOverflow2010 remains.

Full disclosure: I contribute a lot of mostly working code to the open source sp_BlitzCache stored procedure.