Hi Arian,
The Execution Status of your campaign (added in the screenshot) is "Finished Successfully" , In this case you can only set the status to "Cancelled"/"Finished" (by using Actions button). You will not be able to delete this campaign.
However, if the Campaign execution is not "Finished Successfully" and the status is "Active" then you can use the Actions button to change it to "Planned" status and then Delete it.
Regards,
Suman