looks like you either installed it rooted or only did a “soft reset” (not a “hard reset”).
anyway. here’s my uninstall-how-to:
to uninstall our app please proceed as follows:
open avast! Mobile Security, open the settings and select the “avast! Anti-Theft removal wizard”. When it’s done you can uninstall avast! Mobile Security like any other app.
if you no longer have avast! Mobile Security installed and just want to uninstall Anti-Theft you can either reinstall avast! Mobile Security to use the wizard or proceed in these steps:
open your phone’s app manager and uninstall the app with the custom name you chose on installing avast! Anti Theft.
If the uninstall fails please remove the app from the device administrators list (you can find it in your phone’s settings).
to remove root installations of avast! Anti-Theft you can use the “avast! Anti-Theft removal wizard” or use the free tool “Titanium Backup”.
alternatively we offer a uninstall.zip at http://dl.dropbox.com/u/27553331/root%20uninstall.zip
unzip it and run uninstall.bat with your phone connected via USB to the pc. make sure usb-debugging is enabeled on your phone and the phone driver is installed on the PC.
If you do it on the PC where you rooted your phone you usually have these drivers available.