snapcenter snapshoot delete

i have a problem to remove some old policy

i check with poweshell Get-SmBackupReport -policy "BP_BO1_Full"

i get this information

SmBackupId                : 207
SmJobId                   : 604
StartDateTime             : 9/20/2018 12:30:01 AM
EndDateTime               : 9/20/2018 12:32:48 AM
Duration                  : 00:02:47.1711490
CreatedDateTime           : 9/20/2018 12:31:42 AM
Status                    : Completed
ProtectionGroupName       : RG_BO1
SmProtectionGroupId       : 20
PolicyName                : BP_BO1_Full
SmPolicyId                : 56
BackupName                : RG_BO1_fbsapwbo1_09-20-2018_00.30.01.6629
VerificationStatus        : NotVerified
VerificationStatuses      :
SmJobError                :
BackupType                : Log Backup
CatalogingStatus          : NotApplicable
CatalogingStatuses        :
ReportDataCreatedDateTime :
PluginCode                : SMSQL
PluginName                :
JobTypeId                 : 0
JobHost                   :

but this snapshoot i cannot find.

How should i remove this entry so i can remove policy.

thanks for any help.