Archiving is an effective way of organizing your sent campaigns.
All sent campaigns can be found in the Sent tab, and also under the All tab.
Although you cannot delete a sent campaign, you can archive it and it will only show in the Archives tab and be hidden from all other tabs.
To archive your campaign, simply select Manage (cogwheel) → Archive for the sent campaign.
To move a campaign back to the Sent tab, go to the Archived tab and simply select Manage (cogwheel) → Restore.
Although you cannot delete a sent campaign, you can archive it and it will only show in the Archives tab and be hidden from all other tabs.
To archive your campaign, simply select Manage (cogwheel) → Archive for the sent campaign.
To move a campaign back to the Sent tab, go to the Archived tab and simply select Manage (cogwheel) → Restore.