Hi Ismail,

It depends on whether your looking to simply delete, or also backup the data. To delete:

1. Use a file sync rule with a blank folder selection to download from server to device, ensure you have "delete unmatched files and folders", that will delete the contents of the folder you target on the device. You can then schedule the file sync to run as you see fit.
2. Use Javascript. You can loop through each file and folder in a folder on the device and based on other criteria you determine delete the files/folders.

If you do want to save the data, file sync is also the answer as you can set it to download the contents to the server and then delete the contents on the device.

Hope that helps!

You can also delete files based on their creation or modification date. 
In this example, files older than 5 days are deleted.

#!/usr/bin/env js 

var dirPath = 'sdcard/Download';

var dir = new mobicontrol.io.File(dirPath);

var today = new Date();

var oldestDate = new Date(today.setDate(today.getDate() - 5));

dir.listFiles().forEach(file => { if (file.lastModified < oldestDate) { file.delete(); } });