Note: Depending on the configuration of your account, when an objective is still in draft it can be deleted by the individual and their manager. However, for many configurations, draft objectives and confirmed objectives can only be deleted by managers and moderators.
Go to your Objectives tab and click on the objective you would like to delete.
Within the objective pop-up, click the Options menu on the top right, click Delete from the drop-down list and confirm you want to proceed with the deletion by clicking Ok.
This will delete your objective.
Note: Once deleted, an objective cannot be recovered.