Here are the steps for fixing a phone stuck in safe mode:

1. Backup all your important data
2. Uninstall & reboot applications you installed recently, if any
3. Check for any Malware or Viruses
4. Restart in safe mode to disable third-party apps
5. Press and hold the power button until the power off displays
6. Press the power off button
7. Press and hold the volume up and power buttons at the same time
8. When the Samsung Logo appears on the screen release your fingers
9. Press the volume down button when you see the safe mode
10. Release the volume down button and your phone is now in safe mode
11. Uninstall the apps which caused the device to go into safe mode and reboot