Bulk deletion of contacts is not available. The app does not have a "delete all selected" action in the Contacts table. You can only delete one contact at a time.
How to delete a single contact
Go to Contacts.
Right-click the row for the contact you want to delete.
In the context menu, choose Delete Contact under the Management section.
A confirmation dialog will open. Read the warning: deletion is permanent and removes all associated data, including phone numbers, emails, donations, pledges, interactions, notes, list memberships, custom fields, and tags.
Type the contact's first and last name exactly as shown in the dialog to confirm.
Click Delete.
The contact and all their associated records are permanently removed. This action cannot be undone.
If you want to stop contacting someone without deleting them
You can mark a contact as Do Not Contact instead of deleting them. This keeps their record and history in your database but blocks them from being called, texted, or emailed. You can find this option on the contact's profile page.
What "Edit Multiple" does
The Edit Multiple button on the Contacts table lets you apply tags or add contacts to saved lists in bulk. It does not include a delete option.