Tails previously included tools to *wipe* files and available disk space. We removed these tools from Tails 6.0 (February 2024), because we think that they are not reliable enough on modern storage devices, such as USB sticks and Solid-State Drives (SSDs).
Instead, operating systems only mark the space that was used by the deleted file as available for future files, because it is much faster to do. However, the content of the deleted file remains on the device until the operating system reuses the space for another file.
Even if some data could still be recovered from [[spare memory cells|secure_deletion#spare]], overwriting the entire device is especially important if the device is not encrypted.