Why did I get locked out of my tablet by using an app?

I downloaded an app named "Transparent phone screen trick" and i clicked it. Then, my tablet, showed what was in front of me (like a camera), but i couldn't see the apps and the "home" button. So, i restarted my tablet so it will close the working apps, but nothing. Now I'm stuck in the lock screen because i cannot see the keyboard to write my code. Can I delete the app without entering the tablet, like, connecting it with my computer?

Boot into Safe Mode. That should disable the app and let you access the phone.