Delete a contact
First, delete your contact in Google Contacts. Mixmax syncs with your Google contacts every 15 minutes, so Mixmax will “learn” that you've deleted the contact. (Note that Mixmax does not sync your contact groups after you first create your Mixmax account.)
First, open your Google Contacts. Click Mail (or Gmail) in the top corner of your Gmail or Inbox browser, and select Contacts from the dropdown menu:
Then find the contact you want to delete. You may need to look in several of your contact folders.
Click the box next to the contact, click More, then select Delete contact.
If your contacts view doesn't look like the screenshot above, it may look like the screenshot below. Click the dotted line next to the contact you want to delete, and select Delete: