There are a few reasons why sometimes you are not able to delete an Objective / OKR
- If the Objective has a child in the hierarchy, then delete is disabled to avoid orphaned Objectives. Move the child Objective to a new parent (or delete it) and then you can delete the first Objective.
- If the Objective has completed and the Grace Period is over, then the Objective can no longer be deleted. To change the Grace Period see What is the OKR Grace Period?