Can I delete or change annotation fields if they become outdated?

Please do this in Account settings > Annotations and integrations > Annotations. Only Owners, Admins and Accountant roles can change these fields.

You cannot delete your custom annotation fields but you can archive them if you no longer want them to be displayed for new annotations. Annotations for transactions that have been made before the field was archived will remain visible to you. You can change the annotation field name, add new options into drop downs, and archive any options that become outdated.