I think I saw other post about this so try search button above if you have not yet. To my knowledge so far all the apps that did this in the past do not work for the Nexus. Only way to do it safely is to stop your google contact sync in the settings sync tab and clear you contacts storage data under apps in settings then restart your sync. All your contacts should come back with no call log and no frequently called contacts. Let me know if you need more precise instructions on this task.