That would only show for a website, not the phone itself. Sounds like you may have a virus, malware, etc on the device.
Shut it off and then try starting it up in "Safe Mode". If it loads fine in there, then you do have something on the device that needs to be remove. So scan it for malware, viruses, bad apps, etc. Remove the problem and then restart the phone. If this doesn't do it, and it won't go away, then you may need to "Hard Reset" the device.
To get into "Safe Mode" please do the following.
1. First turn off the phone.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something similar.
4. If you wanted disable it, simply repeat the steps above, and you should see "Safe Mode: OFF" rather than on.