Remove Stuck Conferencing Number in Lync

To remove a stuck dial-in conferencing number follow the steps below. These worked for me, I hope they do you you.

1. Open the Lync Control Panel and find the dial-in region for the deleted access number.
2. In Lync PowerShell run get-CsDialInConferencingAccessNumber -region <your region>. You will see the following warning "Cannot find the contact object associated with the entry for line URI "tel:+xxxxxx".
3. From the Lync Control Panel under under "Voice Routing" -> "Dial Plans", assign the region found in step 1 to a Dial Plan.
4. From the Lync Control Panel under "Conferencing" -> "Dial-in Access Number", create a new Dial-in Access Number to match the display number LineURI Primary Language.  The SIP URI can be any unique string.
5. In Lync PowerShell  run set-CsDialinConferencingAccessNumber -Identity <identity e.g. "sip:xxxxx"> -scopetoglobal,  Use the identity you created in step 4.
6. Re-run the PowerShell command from Step 2. This time you should not get a warning, and instead you will see the info for the access number created in step 5.
7. Delete the Dial-in Access Number you created in step 4, and re-run the PowerShell command in Step 6 to verify it is deleted. 
8. Wait for a few minutes, then you should no longer see the dial-in access number in the access number listing.