DeleteCommand is a sandbox setting in Sandboxie Ini. It specifies the command to issue to physically delete the contents of the sandbox. Its primary purpose is to make it possible to plug a third-party secure deletion utility into Sandboxie. See Secure Delete Sandbox.
. . . [DefaultBox] DeleteCommand=%SystemRoot%\System32\cmd.exe /c RMDIR /s /q "%SANDBOX%"
The example is the default setting used when DeleteCommand is not explicitly specified, and invokes the Windows RMDIR command to remove the sandbox folder.
For more examples, see Secure Delete Sandbox.
When specifying this setting, make sure to include "%SANDBOX%" (with quote marks) in the command.
Note: Secure deletion is a privacy measure, not a security measure. Both regular deletion and secure deletion effectively remove undesired software that was collected into the sandbox. See Secure Delete Sandbox.