When you delete a contact, they're moved to the recycle bin for 30 days. After 30 days, all their information stored in contact data fields and Insight data is permanently removed.
Before you start
Things you need to know:
You must have the appropriate permissions to delete contacts.
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.
The contact is moved to the recycle bin and is permanently deleted after 30 days.
Learn more in Delete a suppressed contact.