Go to Private messages (under your name upper right corner)
next to each message is a box (look to the right)
Check those boxes of messages you wish to delete then scroll to the bottom
You will see "selected messages" next to a drop down box Choose delete and then GO
THis will delete all messages in your inbox
next to each message is a box (look to the right)
Check those boxes of messages you wish to delete then scroll to the bottom
You will see "selected messages" next to a drop down box Choose delete and then GO
THis will delete all messages in your inbox