You can edit the ‘Sent from my iPhone’ signature by following these steps;

On your iPhone, iPad, or iPod touch;

  1. Go to Settings.
  2. Tap Mail.
  3. Tap Signature.
  4. Tap on the existing ‘Sent from my iPhone’ text.
  5. Enter a new signature or remove the text message to turn off the signature.
  6. Tap Mail in the top left corner to save your changes.