To disable the "Sent with Spark" tagline, please follow these steps:
- Open Spark Settings.
 - Select Composer > Signatures.
 - Display "Sent with Spark" tagline > Disable the toggle.
 
- Open Spark Settings.
 - Select Composer > Signatures.
 - Display "Sent with Spark" tagline > Disable the toggle.
 
- Tap the menu icon 
  at the top left. - Tap Settings 
  at the bottom. - Select Signatures.
 - Display "Sent with Spark" tagline > Disable the toggle.
 
- Tap the menu icon 
  at the top left. - Open Settings > Signatures.
 - Display "Sent with Spark" tagline > Disable the toggle.