Is there a way to request a refund of a portion of the investors investment?

Yes, you can request a partial return by notating so within the "notes" field of the return request.

Yes, you can request a partial return by notating so within the "notes" field of the return request. For example, you could input:
Investment reduced from $5,000.00 to $3,000.00. Please return only $2,000.00 of this trade.