Please follow these steps:
Start the device in Safe-Mode, there are two ways, if you can't with the first method then use the second one.
First method
Make sure the device is turned off.
Turn on the device normally via Power button.
Immediately after turning on the power, press and hold the VOLUME DOWN button until you see the unlock screen.
The safe mode will be indicated with a semi-transparent message "Safe Mode"
Second method
Make sure the device is turned off.
Turn on the device normally via Power button.
During boot, press and release continuously the "
left soft touch" untl you see of the main screen of the phone.
Now you are in safe mode
Go to Settings -> Apps (or Application Manager).
Now you must locate the infected application and this may have different names.. Here some of these: System Update, BaDoink, Video Player, Tube Mate, Network Driver System, Video Render, PornDroid..
Or one of the last applications you have installed that may have infected the device.
Press on the app and then on Uninstall.
Now restart the device again (
not in Safe-Mode).
NOTE: if you are not able to press on Unistall tab, then here is how to proceed:
Go to Settings -> Security -> Device Administrators
Remove the flag from the application that you want to uninstall and press “Deactivate“.
Now you should see enabled the item “Uninstall”