I have a death certificate and I'd like to get it delivered to the correct place.
I think you've misunderstood the nature of FamilySearch's Family Tree. There isn't an authority or official entity that does things: it's an open-edit communal tree. If you'd like to add something to it, just log in and do so.
Additional information to edit a death date and add an outside source:
To add your spouse's death date, follow these steps:
To add his death certificate as a outside source, follow these steps. Simply navigate to the ancestor's Person page, on the website or through the FamilySearch Family Tree app. Then click or tap the tab labeled Sources. Follow the prompts that follow for adding a source.
For more details check here:
Thanks for your attention in keeping the tree up-to-date.