To delete a work log attribute, press the trash icon that appears when hovering on the attribute you want to delete. A confirmation dialog will be displayed. We strongly suggest you to simply disable the attribute instead of deleting it. You can easily re-enable a disabled attribute later without loosing losing any information. If Disabling a worklog attribute is reversable, you can simply re-enable it. But if you delete it, this attribute is also removed from all of the previously entered work logs. Work logs themselves are not deleted, only attributes are deleted.
...
there is no way to bring it back.
...