How to bulk delete contacts
Use a file upload to bulk delete
Go to Workflows > Data flow. You can also access it from Admin console > Workflows > Data flows
Create a new data flow with following source and destination
Source: CSV Upload
Destination: Delete contact

Once created, you will need to add the following in JSONATA expression if your key identifier is phonenumber:
If your key identifier is emailaddress:

Upload file to delete
Now, you can export contacts from a list or segment or the contacts page, and upload here in the data flow.
Click on Save and then click on Run Now
You can Edit data flow to upload more files and then again click on Save > Run Now.
