Del. Code tit. 29, § 2710

The State Treasurer shall cause any agent so designated by the issuing officers to maintain reconciliation statements on all state bonds and coupons. Said reconciliation statements shall balance with bank statements on bond and coupon accounts. Any paid-off, matured, redeemed, called or cancelled bonds and coupons shall be held by any agent so designated by the issuing officers on behalf of the State Treasurer until a sufficient quantity has been collected by the office to be cancelled and destroyed according to this chapter.