I sorted two solutions out for making the divider( delimiter) invisible :
1- Use:
tabHost.getTabWidget().setDividerDrawable(null);
2- Set android:showDividers="none" on TabWidget , like :
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="60dp"
android:gravity="bottom"
android:layout_alignParentBottom="true"
android:fadingEdge="none"
android:showDividers="none" >
</TabWidget>