Cleans all pages in all files of the database.
Under some circumstances, the deleted rows can physically remain on the data page as a ghost records.
You can use sp_clean_db_free_space to clean these ghost records.Before you run sp_clean_db_free_space, it is recommend to create a full database backup.
Example
USE Master
GO
EXEC sp_clean_db_free_space @dbname = N'YourDBName';