delete specific folder on a user mailbox exchange 2013

I meet a Lync bug the lync contact is duplicate with 3 thousand contacts record and the contact folder is read only, it can't delete on outlook client, even I disconnect the connection between Lync client to outlook client. It need delete on OWA mode.

I run the below exchange powersehll with export-mailbox which died already on exchange 2013.

get-mailbox -Identity name | Export-mailbox -DeleteContent -IncludeFolders "\Inbox"

Any advise?

Thanks.