How do I delete a contact?

When you are at Community > Contacts and the list of all your contacts, highlight the desired contact. Scroll all the way to the Right to the Delete (trash can icon).  This will delete the contact and all activity records (Donations, Interactions, etc.) in its entirety. 

Alternatively you can "InActivate" the Contact if you do not want to permanently delete their record. Highlight the desired Contact. Click the Contact tab, UN-check the "Active" box.