Learn more about the Settings > Custom Applications section:

Torii provides a comprehensive database of SaaS applications, but you also have the flexibility to add custom apps as needed.

After clicking "+ Add application" you will be asked for the custom app's name and details.  Hovering over an entry in the list will expose buttons to Hide or edit the app.

To get started, we recommend reviewing Adding and Editing Custom Apps for a detailed introduction to this feature.