Delete ALL data From DATABASE

Execute the following query:(in new  query editor ):

EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' 
GO 

EXEC sp_MSForEachTable 'DELETE FROM ? WHERE 1 = 1' 
GO 

EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' 
GO

EXEC sp_MSforeachtable "DBCC CHECKIDENT ( '?', RESEED, 0)"