Refer to the Basic configuration page that explains how to setup your Applications, your Categories and your Environments.
In order to update and Environment, you have to double click on the line of the Environment, or click on the Edit Environment menu entry as shown below.
On the General tab, the basic elements can be updated.
On the Attributes tab, the attributes can be added and updated. In order to add new attributes, refer to the Attributes section.
In order to delete an Environment, you can click on the Delete Environment menu entry as shown below.
In order to delete the Environment using the Delete button, there should be no issue associated to that Environment. Clicking on the link highlighted below will display all the issues associated to the Environment.