Currently there is no OpenSTAAD function available to modify or delete the design parameters. We have informed our development team about your requirement.
Meanwhile, you can use the following function to extract the design parameter assigned to a member--
Design.GetMemberDesignParameters nBriefRef, nMemberNo, pDesignParams
Meanwhile, you can use the following function to extract the design parameter assigned to a member--
Design.GetMemberDesignParameters nBriefRef, nMemberNo, pDesignParams