How to change the valus of a field (example phone value to text)

How to change the valus of a field (example phone value to text)

Hi
I want to change or replace the values of the field that I have, for example I have the field Phone, and I want to converted or replace it original value to a value "text"

I want to do this because I am using a Ninja Form and when I use the mask value for phone number in that form CRM it does not recognized that field.

I tried to delete the field "Phone" and add a new field with value text, but the Enterprise edition does not allow me because said that I am reach the field amount for my enterprise paid application.

Can somebody help me please
Thanks a lot
Danny