There is no statutory requirment under either the FDCPA or the FCRA that requires a debt collector to delete their reported collection once their collection authority is termianted, such as by sale of the debt.
The "requimrent" is an administrative credit reporting instruction contained in the standard credit reporting manual used by the big-3 CRAs.
The CRAs established that policy in order to preclude two collections from simultaneously showing in a consumer credit report on the same debt, should a new debt collector report.
Debt collectors are often a bit lax in complying with that administrative instruction. A call to them or a complaint/dispute with the CRA may be necessary, but in the end, you can use the CRA policy as means to get deletion.
