Luckily, Android's lock screen has deep dependencies (purges in-memory passwords for VPN, for example), so it can't be disabled be an app. That said, it can be

Luckily, Android's lock screen has deep dependencies (purges in-memory passwords for VPN, for example), so it can't be disabled be an app. That said, it can be prevented from appearing due to a timeout. Pressing the power button should always lock your phone.