Modern SSD controllers can relocate writes through wear leveling. APFS can use snapshots and copy-on-write behavior. Backups, cloud services, messaging, exports, and collaborators can hold separate copies.
Secure Remove acts on the selected accessible file under the capabilities of its storage and macOS. It cannot promise destruction of:
- Historical snapshots.
- Backups.
- Cloud versions.
- Copies on other devices.
- Previously exported or shared files.
- Physical blocks hidden by storage hardware.
For high-assurance retirement, follow organizational policy and hardware-level erase or destruction guidance appropriate to the device.
Never treat routine cleanup language as a legal guarantee of universal erasure.