Cancel AP1

we need to cancel a registration application (eAP1 ), we have already made a note on the land registry portal but have not received any update. could you please let us know the fastest and convenient process of cancellation

You need to request cancellation using our contact channel - Guidance and support for property professionals - GOV.UK
There's a specific option to request cancellation of an application
If you use reply to requisition/portal then your request/message won't be read until processing actually starts