Removing event handlers

I am having a problem that would probably be fixed by removing event handlers from the form but i am not sure. Ok here is my problem, when i am adding a contact to an existing account, CRM automatically auto fills the phone number field with the phone number in the account details. Is there a way to stop it from auto filling since most of the time the contact phone number is not necessarily the same with the account details. I am using CRM 2015 online.