How to delete specific range of data from Service Broker > System Queues data table?

Question

Due to sudden increase of my database .mdf file we found there are 4 internal queue message table are increase unexpectedly. so we decided to delete some range of data from these table.

we try this code:

declare @c uniqueidentifier
while(1=1)
begin
    select top 1 @c = conversation_handle from dbo.queuename
    if (@@ROWCOUNT = 0)
    break
    end conversation @c with cleanup
end  

but its try to delete all data and due to space limitation this query cannot execute. my internal message queue table :