Access
Open For developers → your application → Access. Here you can allow individual projects to install a private plugin. To list it in the public catalog, see publication.
Only the application owner can grant and remove private access. An invited developer can view the list. See application roles.
The screenshots show a demo application with fictional data.
Grant access
In Access, check the application status. For private use, click Invite. In Invite Person, enter the project identifier in Id. Check the matching project name before confirming. The application then becomes available in that project's private catalog; installation and permission consent are separate steps.

Remove access
Find the intended entry, open its ⋯ menu and choose Remove.

Review the access removal confirmation. After a successful response, check the updated list.

This removes the entry from the private access list. An existing project installation, its templates and issued tokens remain. To disconnect an installed plugin from a project, remove the installation in that project.