Remove BlackBerry throttling policy from Exchange 2010

Find all mailboxes with the "BESPolicy"

Get-Mailbox -ResultSize Unlimited | where {$_.ThrottlingPolicy -eq "BESPolicy"}

Note - The policy name is capital sensitive

Set all found mailboxes to the default throttling policy

Get-Mailbox -ResultSize Unlimited | where {$_.ThrottlingPolicy -eq "BESPolicy"} | Set-Mailbox -ThrottlingPolicy DefaultThrottlingPolicy_7371b684-08b6-4d0a-9116-34ade049caf8

Remove the BESPolicy

[PS] Get-ThrottlingPolicy BESPolicy | Remove-ThrottlingPolicy

Confirm
Are you sure you want to perform this action?
Removing throttling policy "BESPolicy".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"): y