uninstall app silently with system privileges

Here is how I did it:

ApplicationManager.java (changed part):

private PackageInstallObserver observer;
private PackageDeleteObserver observerdelete;
private PackageManager pm;
private Method method;
private Method uninstallmethod;

 class PackageDeleteObserver extends IPackageDeleteObserver.Stub { 

    public void packageDeleted(String packageName, int returnCode) throws RemoteException {
        /*if (onInstalledPackaged != null) {
            onInstalledPackaged.packageInstalled(packageName, returnCode);
        }*/
    }
}
public ApplicationManager(Context context) throws SecurityException, NoSuchMethodException {

observer = new PackageInstallObserver();
observerdelete = new PackageDeleteObserver(); 
pm = context.getPackageManager();

Class<?>[] types = new Class[] {Uri.class, IPackageInstallObserver.class, int.class, String.class};
Class<?>[] uninstalltypes = new Class[] {String.class, IPackageDeleteObserver.class, int.class};

    method = pm.getClass().getMethod("installPackage", types);
      uninstallmethod = pm.getClass().getMethod("deletePackage", uninstalltypes);
}
public void uninstallPackage(String packagename) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {
uninstallmethod.invoke(pm, new Object[] {packagename, observerdelete, 0});
}

PackageDeleteObserver.java (in android.content.pm):

package android.content.pm;

public interface IPackageDeleteObserver extends android.os.IInterface {

    public abstract static class Stub extends android.os.Binder implements android.content.pm.IPackageDeleteObserver {
        public Stub() {
            throw new RuntimeException("Stub!");
        }

        public static android.content.pm.IPackageDeleteObserver asInterface(android.os.IBinder obj) {
            throw new RuntimeException("Stub!");
        }

        public android.os.IBinder asBinder() {
            throw new RuntimeException("Stub!");
        }

        public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags)
                throws android.os.RemoteException {
            throw new RuntimeException("Stub!");
        }
    }

    public abstract void packageDeleted(java.lang.String packageName, int returnCode)
            throws android.os.RemoteException;
}

Also dont forget to add permission to manifest:

<uses-permission android:name="android.permission.DELETE_PACKAGES"/>

Working sample project (apk need to be placed in “/system/app” path on device):
http://www.mediafire.com/file/no4buw54ed6vuzo/DeleteInBackgroundSample.zip