Is it permissible to claim the penalty clause agreed upon in the partnership contract if one of the partners unilaterally rescinds the contract without the consent of the other?

It is forbidden for a partner to stipulate to their partner a guarantee of their capital and an increase upon dissolving the partnership. Such a condition is considered void, for every condition not in the Book of Allah is void. The partnership has been dissolved and concluded, and the aforementioned condition is void, so you are not entitled to demand it from your partner.