Is there a way to scrub the free space of a drive, several times in a day, in Windows 7, without using scheduler? It would be preferred to use Group Policy and something that can be pushed to the clients! The idea is to not allow the users to stop this process.

We cannot realize it via GPO. The most easy way is using Task Scheduler. You can change policy settings to not allow users to enter "Disk Management" console. The policies are under User Configuration\Administrative Templates\Windows Components\Microsoft Management Console You may refer the following article. Setting Group Policy in MMC If you only need to manage certain computers, you can do it directly from any computers. In the system, click Start, in the Start Search box enter "mmc". Then, click File->Add/Remove Snap-in. Add the Disk Management snap-in and set to manage a client computer. Then you can manage the disk on that computer.Arthur Xie - MSFT