When attempting to conclude the interaction, if available, attempt to lead with attractive solutions, positive options, reasonable compromises, or provide access to individuals who may have a greater authority to resolve the issue.
If those options are unavailable, it is important to clearly and calmly explain why you cannot be of assistance, such as being bound by legal requirements or organizational policy directives.
Regardless of whether the attempts at resolution are received positively or negatively, closing also involves setting clear expectations about next steps. If they are positively received, explain what and when actions will occur to solve or mitigate the issue. If negatively received, be clear in calmly explaining the consequences of non-compliance or continued confrontational behavior.
As always, it is essential to remember during high-stress interactions that safety is the top priority. Achieving the goal of de-escalation requires the willing participation of ALL the parties involved. Unfortunately, some people, despite your best efforts, will choose not to participate. Once you recognize that the interaction is unlikely to improve and actually may worsen, it is important to have a strategy in place, such as asking for assistance from another staff member or even calling law enforcement, in order to end this interaction while maintaining your safety.
But setting the appropriate tone, displaying empathy, and being sincere in your efforts to achieve resolution all enhance the likelihood of keeping potentially contentious interactions calm, safe and productive.