Note: Package frequencies that are added as packages on accounts (account-packages) are in use and cannot be deleted. However, you can deactivate a package frequency by unchecking the 'Active' checkbox in the Edit Package Frequency panel. Deactivating a package frequency that is in use will not impact existing accounts, the deactivated package frequency will simply not be available when adding packages to accounts going forward.
Select the package frequency you wish to delete in the list on the left under the Packages heading
On the left under the Packages heading click the icon
On the confirmation dialog click Yes to confirm that the selected package frequency should be deleted