Option - I: (resign from the directorship)
You can resign the post of directorship from the company. inform your decision by written to the board.so that you cannot be personally held for any ultra vires act from now on. upon acceptance of resignation by board, inform all your clients and creditors.
if at all there was any ultra vires act during your tenure as director you can be personally held liable for such acts, i think you are willing to accept such liabilities.
Option - II: voluntary winding up of the company.
A voluntary winding up requires a special resolution to be passed at the general meeting. in order to pass a special resolution 3/4 majority is required.
option - III: Compulsory winding up (in case other shareholder are not willing to wind up)
If you have good relationsship with the creditors then you can them to make an application in court of law for winding up of the company for a reason, company's inability to pay the credit. you need to carefully follow the due course of law.