Pipedrive field attributes changes

We've been using the Pipedrive CRM for about 10 years. We have 209 fields, most of which are default fields. The problem we are is facing is that the default fields cannot be edited and provide very little flexibility. We are seeking a Freelance that would be able to change our default fields to custom fields attributes. We'd like to delete or hide some of the default fields, resulting in a CRM that only displays the relevant fields needed. We wish to ensure that all of the current work will be saved and protected, and that our current users (6) can ''ideally'' still use the CRM while the work is being done on the back end.