- If you have all the contacts in a data extension then you can go to
All contacts > use the delete icon to select the data extensions to
Note - You would need to enable contact deletion before you delete. Also, you can only delete only one million records at a time. So, you can use the below SQL query to segment it by rows. Just change the the row number every time.
select x.* from (Select D.Subscriber_Key, D.email_address ,ROW_NUMBER() OVER ( ORDER BY D.Subscriber_Key) as row
from [Name of the data extension] as D)x
where x.row > 0 AND x.row <= 1000000
Reference - https://help.salesforce.com/articleView?id=mc_cab_delete_contact.htm&type=5
- If you don't have contacts in the data extension then you can raise a
case to salesforce and they can get you the records in csv file. Post
that you can import into data extensions from SFTP and delete the
contact using the data extension
- You can also use the REST API to do the delete.
Reference - https://developer.salesforce.com/docs/atlas.en-us.mc-apis.meta/mc-apis/DeleteByContactKeys.htm
Let me know if this helps.