If your Clan Leader seems to be inactive, and your clan is therefore not going anywhere, there are a few routes available.

Since there's no way to demote a Clan Leader, your best option might be to create a new clan. Consider using the clan chat to connect with your clan mates via Game Center, Google Play or Facebook. This way, you can invite them to a new Clan and start afresh.

Consider connecting with the Clan 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 the Clan needs help.