Hello Jemima - you would list any documents you are lodging so that would depend on whether you have any and need to lodge them. You know that the Unilateral Notice is protecting X so you need to show how that protected interest has come to an end. That can and does vary depending on the protected interest (the option agreement and the Ts & Cs therein for example.
Notices, restrictions and protection of third-party interests (PG19) - GOV.UK (www.gov.uk)
We don't need a copy of the register itself as we hold that ourselves.