I cannot uninstall the app

You have probably activated uninstall protection in CAPTCHA Cheating prevention.

This option registers the app as a device administrator in order to block turning off the phone when an alarm rings.

Go to System settings → Location and Security → Device Administrator and deselect the admin which you want to uninstall.
or disable Force stop and uninstall protection in Settings → Alarms → Captcha → Captcha No Cheating (might be hidden under Advanced menu)

Now uninstall the application. If it still says you need to deactivate the application before uninstalling, you may need to Force Stop the application before uninstalling.g

Tags: uninstall, captcha