https://docs.fedoraproject.org/en-US/package-maintainers/Package_Orphaning_Process/#orphaning_procedure currently says:

go again to the settings tab for your package’s Pagure repository. Navigate down to the Give Project section and give the project to ... the orphan user

The instructions should navigate the maintainer to the main page of the project on Pagure, left column, click the Orphan button, and fil in the reason why the package was orphaned.

The currently documented way of doing it works but leaves the reason blank.