This article explains how to delete many iPhone contacts at the same time directly via using a PC program called CopyTrans Contacts. The method works for deleting both local iPhone contacts and contacts sourced from cloud accounts such as iCloud, Gmail, or Yahoo.
Download CopyTrans Contacts from the following page Delete multiple iPhone Contacts
Install the program. If you need help installing CopyTrans Contacts, please refer to this article
Run CopyTrans Contacts and connect your iPhone. Your iPhone contacts will appear in the program’s main window.
Note: if you don’t see some or all of your contacts in the program window, please have a look at this article
Select the contacts you wish to delete from iPhone. To select several contacts at the same time, tick the checkbox next to each contact you want to delete. To select all contacts at once, check the box next to “Contacts” on top of the list
Right-click on the selection and choose “Delete contact(s)”. You can also delete the selected contacts by clicking on the small red “X” on top of the contacts list
That’s it! You have now managed to delete multiple iPhone contacts at once directly from your PC.
Delete multiple iPhone contacts synced via iCloud, Gmail, or Yahoo
CopyTrans Contacts can also help you permanently delete multiple iPhone contacts synced via cloud accounts such as iCloud, Gmail, or Yahoo.
The method is the same as above but you first need to connect your iCloud, Gmail, or Yahoo account where the contacts you wish to delete are contained. To connect a cloud account with CopyTrans Contacts follow the quick steps provided in this tutorial: Why connect to my cloud account in CopyTrans Contacts
Deleting multiple contacts on iPhone – YouTube video guide