Unable to delete plan "PreProd test" on MATT getting below server error.

ErrorID : 0
ErrorSource : ControllerAppTier.Delete->BenAdminControllerAppTier.Delete->BenefitPlanDesign.Delete->BenefitPlanDesign.DeleteBenefitPlanDesign
ErrorMessage: The DELETE statement conflicted with the REFERENCE constraint "FK_ContingentEligibilityRules_PlanDesign". The conflict occurred in database "MATT_11878", table "dbo.ContingentEligibilityRules", column 'PlanDesignID'.
The statement has been terminated.

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CC: Mandar Kulkarni, Satya, Prasad Patil, Rakesh Roy