To empty the "Trash" or equivalent areas on your iPhone, follow these steps for various apps:

For Files:

  1. Open the Files app.
  2. Tap Browse at the bottom of the screen.
  3. Tap Recently Deleted.
  4. Tap the three dots in the top right corner, then choose Select.
  5. Choose the recently deleted items you want to permanently delete.
  6. Tap Delete, then confirm by tapping Delete once more.

For Mail:

  1. Open the Mail app.
  2. Locate the Trash mailbox under Mailboxes.
  3. Tap the Trash mailbox.
  4. Tap Edit at the top.
  5. Tap Select All or individually select messages.
  6. Tap Delete at the bottom.

For Notes:

  1. Open the Notes app.
  2. Tap Folders > Recently Deleted.
  3. Tap Edit.
  4. Tap Delete All to permanently delete notes.
  5. Confirm by tapping Delete Notes.

Please note that the iPhone does not have a universal "Trash" folder for all types of files, so you'll need to follow these steps for each app where you want to empty the trash.