In which case does the customs declarant be allowed to carry out customs procedures for export and import goods registered once?

Question: I have an import shipment, the shipping company changes the port of discharge, but does not send me information about port changes. I opened the import and customs clearance declaration form according to the original port. Now I should fix the post-clearance declaration or cancel the declaration (taxable goods). How to fix the declaration?
Answer:
In this case, due to wrong port code, the declaration cannot be corrected, the wrong declaration must be canceled and the new declaration must be opened and the reason for cancellation of the declaration must be clearly stated in the cancellation letter.
Methods to cancel declarations:
- Follow the manual method
Step 1: The customs declarant requests to cancel the registered customs declaration.
Step 2: Customs authorities consider canceling the registered declaration.
Step 3: The customs office will cancel the customs declaration: Cross out with ink, sign and seal the civil servant on the customs declaration to be canceled.
Step 4: Customs office notes on the system: this declaration has been canceled
Step 5: Customs offices keep customs declarations canceled in the order of registration numbers.
- Follow the electronic method
+ For customs declarants:
 Customs declarants create information to cancel declarations in accordance with the form of information Declaring the declaration, stating the reason, sending to the customs office through the customs electronic data processing system, receiving "Notice of instruction electronic customs procedures ”and make requests to create customs clearance instructions.
Customs declarants must submit to the customs office 01 printed electronic customs declaration; the annexes of the declaration, the statements, and the paperwork check form, the goods inspection slip (if any) in the case of printed e-customs declaration has been confirmed "Goods have passed the monitoring area" for export and / or "clearance" or "release of goods" or "Deliver goods for preservation" or "Allow export and import goods to be transferred to border gate" for export goods, import.
+ For customs authorities:
The customs office performs the cancellation of the declaration and feedback to the customs declarers for the following declarations that the customs declarer does not carry out the procedures to cancel the declaration:
o Past 15 days from the date of registration, issue the customs declaration number without presenting the e-customs dossier in case the e-customs dossier must be presented.
o Past 15 days from the date of the customs declaration registration, the customs declarer has not yet presented the exported or imported goods and has to check the customs offices for inspection.