If you want to edit a Custom Form for Cases but are unable to do that because there are fields in the form that have been used, you should replace the old Custom Form for Cases with a new version of the Custom Form for Cases.
There are 3 stages to this process
Create a new Custom Form for Cases that contains the old fields you want to keep and any new fields you want to add
Assign the new Custom Form for Cases to the projects you want it to be assigned to
Unassign the old Custom Form for Cases from the projects it was assigned to
Steps to follow
PART 1: Create a new Custom Form for Cases that contains the old fields you want to keep and any new fields you want to add
Select Create in the top menu
Select Show more options until the menu expands
In the expanded menu, select Custom Form
Name your Custom Form
(E.g. “[name of the original form]: v2”)
Select Cases (rather than Contacts) in the type dropdown list
Press Save
You arrive on the Manage Fields page
In your library on the left: select the fields from the old Custom Form that you want in this new form
If you need to create any brand new fields, use the Create field button to create them
PART 2: Assign the new Custom Form for Cases to the projects you want it to be assigned to
Go to the Manage Custom Forms page
Press the Preferences button next to the Custom Form you just created
You arrive on the Custom Form’s Preferences page
By default, all of your organisation’s projects are included.
De-select the projects that you do not want the Custom Form for Cases to be used on.
Press Save
PART 3: Unassign the old Custom Form for Cases from the projects it was assigned to
Go to the Manage Custom Forms page
Press the Preferences button next to the old Custom Form for Cases that you want to stop using
You arrive on the Custom Form’s Preferences page
The projects that this Custom Form for Cases has been assigned to are shown in the Select Projects box
De-select every project until the box is blank
Press Save