What should we do with the dues of the partner who refused to collect his profits after leaving the company; should we incorporate them into the company or donate them?

The dues of a partner are a trust (amanah) and may not be disposed of except with his permission. If the partner refuses to take them, then one can discharge their responsibility by placing them with a legitimate authority, such as a judge, or by placing them with the partner in the presence of witnesses and informing him of this.