Can not get rid of old and/or erroneous contact data

Can not get rid of old and/or erroneous contact data

Zoho mail seems to keep all contact data forever irrespective of edit or delete attempts.  Contacts that I deleted still come up when I search contacts or type a name in the "To" of an email.  Also, if I made a mistake when entering a new contact's email address and save it, then later I edit the contact to correct it, email will still insert the erroneous address into the "to".  When I make a mistake on the contact name, save it, and then edit it later, the revised name is never found when I search contacts, only the original erroneous name.  I've tried deleting the contact and starting over but the old data still comes up on a contact search and I never see the revision.  When I do a search and a deleted contact appears, when I click the contact, there is no contact data?  Zoho mail seems to have a contact memory somewhere that can not be deleted or altered.  How do I fix this?