Hi Saddam,
There are two ways to get this done that I know of. Assuming you’re working primarily in a sandbox:
- Comment out all the lines with that field in it in all classes and triggers.
- Modify the field.
- Deploy all the changed code and metadata to production
- Uncomment all those lines of code
- Deploy all the changed code to production
or
- Make a new field with a new name.
- Change every reference in your code to that new field.
- Deploy changed code and new metadata to production
- Move over any data from the old field to the new field