If you delete the FromDate and ToDate in the parameter tab, then the Update button will go away.
Then in your SQL code for the report, set the date range like this, so the SQL script will get the current date automatically, instead picking up from the macro value in the parameters.
SELECT [Date] AS StartTime ,T1.Hits FROM
{%DatabaseSchema%}.Func_Analytics_EnsureDates ({%DatabaseSchema%}.Func_Analytics_DateTrim(GETDATE()-30,'day'),GETDATE(),'day') AS Dates
LEFT JOIN
...