If your Task Force leader seems to be inactive, and your Task Force is therefore not going anywhere, there are a few routes available to take.
Since there’s no way to demote a Task Force leader, your best option might be to create a new Task Force. Consider using the Task Force chat to connect with your Task Force mates via Game Center, Google Play or Facebook. This way, you can invite them to a new Task Force and start afresh with even more power!
You may also consider connecting with the Task Force leader on social media if you haven’t done so already. If you can contact them through some other communication channel, you can let them know that he should come back to at least hand over leadership to somebody else in the Task Force.