Cannot access settings on Xperia Acro S

Avast Mobile Apps Avast Anti-Theft for Android
1

A few months ago everything was working fine. Now

  1. I cannot dial the pin to get to the settings dialog. Just the normal dial panel opens with “unknown number”.

  2. I cannot uninstall from the apps list, as the button is disabled.

  3. I cannot send a “settings” command from the web app, because it says the phone is not communicating. I restarted the phone, no change.

  4. I cannot reinstall it through the play store, as it says “deactivate”. When I press this, the message comes: “This app is a device administrator and must be deactivated before uninstalling”. Great, didn’t I just press that?

I am screwed - cannot open settings, cannot uninstall. What’s the back door to get rid of this thing?
Btw, don’t know if it matters: my phone is rooted

2

Can nobody help me?
How can I desinstall AntiTheft on my mobile phone and reinstall it?