delete a relation by API

Hi to all, i’m importing 2 csv, Accounts and Contacts via API, i’m in the situation to create the relation between 1 contacts to 1 account. Actually my problem is set the Deleted column to 1 when i update the relation, cause seems i can’t use Accounts_contacts to make query except the set_relationship. There is a way to set all the old relation to delete and then create ne new ones?

thank you all