Using the button Show Database List or menu Databases | Database List will show a screen similar to the one below.
The Database List with columns for extra information
In case you need to modify the database registration parameters, you can select an entry and use the Edit Registration Details button or double click it.
You can test the database connection from this list if you like.
If you want to remove an entry, use the Delete Registration button, if the database is used by a project, you'll get an error message saying so.