Before you start
Things you need to know:
Deleting a contact moves the contact to the recycle bin for 30 days. After 30 days, all of their information held in contact data fields and Insight data is permanently removed.
Delete a single contact
To delete a contact on the Single customer view:
Go to Audience > Contacts.
Find and select the contact you want to delete.
On the Single customer view, expand the CONTACT ACTIONS drop-down menu.
Select Delete this contact.
Read the delete confirmation information, and select the confirmation check boxes.
Select DELETE.
Learn more in Delete a suppressed contact.