Is there a way relinquish founder's stock or force the company to take it back?

I was a cofounder of a Delaware C corporation. There was a falling out on the founding team about some questionable business dealings. Several of us resigned, but are now concerned that the remaining shareholder is creating liabilities that might come back on shareholders such as unpaid taxes, etc. We'd like to be done and clear of any relationship with the company, but we do not hold enough stock to to force an action by written consent of the shareholders. Any ideas on how we can cut any relationship we have with the company and its actions?