DELETE FROM [dbo].[EventLog];
-- or
TRUNCATE TABLE [dbo].[EventLog];
DELETE FROM [dbo].[SiteLog];
-- or
TRUNCATE TABLE [dbo].[SiteLog];
-- or delete just elder than 30 days
DELETE FROM [dbo].[EventLog]
WHERE [LogCreateDate] <= DATEADD(day, -30, GETDATE());
DELETE FROM [dbo].[SiteLog]
WHERE [DateTime] <= DATEADD(day, -30, GETDATE());