legal ground
Article 35 of the Measures for the Administration of Urban Real Estate Mortgage
When the mortgage contract is changed or the mortgage relationship is terminated, the parties to the mortgage shall, within 05 days from the date of change or termination, handle the change or cancellation of mortgage registration at the original registration authority. If the mortgaged real estate has obtained the land use right and the ownership of the above-ground buildings and other attachments after being punished according to law, the mortgagor shall, within 30 days from the effective date of the punishment, apply to the real estate management department of the local people's government at or above the county level for the registration of the transfer of house ownership, and apply to the land management department of the people's government at the same level for the registration of the change of land use right by virtue of the changed house ownership certificate.