The best person to own the unmitigated risk of the technology is the IT system owner. The IT system owner is the person or entity that has the authority and responsibility for the acquisition, development, maintenance, and operation of the IT system. The IT system owner is also responsible for ensuring that the IT system meets the business requirements, security standards, and compliance obligations of the enterprise. The IT system owner should own the unmitigated risk of the technology, as they are in the best position to understand the nature and impact of the risk, and to implement the appropriate risk responses to reduce the risk exposure to an acceptable level. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter
1, Section 1.3.1, page 251234

A three lines of defense structure is a model that defines the roles and responsibilities of different functions and levels within an organization for risk management and control. The first line of defense is the operational management, which is responsible for owning and managing the risks. The second line of defense is the risk management and compliance functions, which are responsible for overseeing and supporting the risk management processes. The third line of defense is the internal audit function, which is responsible for providing independent assurance on the effectiveness of the risk management and control systems. The greatest benefit of a three lines of defense structure is that it provides clear accountability for risk management processes, as it clarifies who is responsible for what, and how they interact and communicate with each other. This can help to avoid duplication, confusion, or gaps in the risk management activities, and ensure that the risks are properly identified, assessed, treated, monitored, and reported. References = CRISC Review Manual, 7th Edition, page 107.

Introducing control procedures early in the IoT solution life cycle ensures proactive identification and mitigation of risks. This approach aligns with Secure System Development Practices and Risk Mitigation Strategies, reducing exposure as the solution evolves.

The risk associated with data loss from a website which contains sensitive customer information is best owned by the business process owner, as they are ultimately responsible for the business objectives and outcomes that depend on the website. The business process owner should ensure that the website is adequately protected and that the customer data is handled in compliance with the relevant laws and regulations. The third-party website manager, IT security, and the compliance manager are all involved in managing the risk, but they are not the owners. The third-party website manager is responsible for the technical aspects of the website, such as hosting, maintenance, and performance. IT security is responsible for implementing and monitoring the security controls and policies for the website. The compliance manager is responsible for ensuring that the website meets the regulatory and contractual requirements. However, none of these roles have the authority or accountability to own the risk, as they are not directly affected by the business impact of the data loss. References = Risk and Information Systems Control Study Manual, Chapter 2: IT Risk Identification, page 47.

A key performance indicator (KPI) is a metric that measures the achievement of a specific goal or objective.
A KPI for the internal control that requires all access for employees be removed within 15 days of their termination date could be the percentage of employees whose access was removed within the specified time frame. This KPI would help the risk practitioner to monitor the compliance and effectiveness of the control and identify any deviations or issues.
References
*Key Performance Indicators (KPIs) - ISACA
*How to Improve Risk Awareness in the Workplace [+ Template] - AlertMedia
*[SITXWHS