In the Contact Section, you can edit the information on a Contact that you have already created. Open up your contacts and select the one you are wanting to edit.
Open up the contact that you are wanting to edit by clicking on View and you will be brought to their record like below.
On the record there will be a button called Edit that will bring up another box that will allow you to edit the information of the selected contact such as the contacts name, telephone number and email address. It will also let you select whether or not the contact is currently in use.
Once you click update at the bottom of the page the contacts information will be changed.