Hello there and welcome to the Wowza support forum.
When the window duration is set to 24 hours, anything outside of that window is purged when recording. It will not delete previously recorded files that are on the disk from previous days.
The Application.xml /DVR /WindowDuration is set in seconds, so this is one hour:
This WindowDuration value applies to the duration length of the current recording. Other DVR Stores will not be affected. So if you have other DVR Stores on your hard drive that were recorded separately, even with the same WindowDuration, those Stores will not be affected by the purging related to the current recording. Any other file maintenance will need to be done outside of Wowza. To delete other Stores from your hard drive, you can delete the entire Store with a cronjob or any other method you use for system maintenance. We don’t have anything built-in to Wowza for this.