This feature has been removed since OJStat version 1.3.
Then, what is meant by old data in OJStat? What is meant by old data is data on visits to a journal that is no longer needed, for example data that is more than 7 years old. These data are all stored in your OJStat database. Even though the OJStat database is the smallest database that won't take up space, it might be a good idea to clean up old data to make it easier to read the visit graph (eg in a widget) view. Of course, this is your choice and most people don't want to delete the visit data their journals get.
OJStat wants to serve everyone in this regard, whether they want to delete old data or not. If by chance you want to delete old data in OJStat, you must understand that the deleted data is not general but specific to the journal in question. Therefore, deletion of old data can only be done through the journal configuration page in OJStat, especially on the Delete Old Data tab.
When you enter the old data deletion page on OJStat, please select two dates, namely the start and end dates of the data you want to delete. The form used is very easy and clear, but if you enter it wrong, OJStat may delete the wrong data. Therefore, you must be very careful in deleting data in OJStat.