Disk expansion

I hadn't read up on the proper instructions in time http://kb.fortinet.com/kb/microsites/search.do?cmd=displayKC&docType=kc&externalId=FD40848 and I went on the VM side and just upped the amount of space in what Analyzer sees as "disk1" So then I tried going back to the VM side and I couldn't lower the amount of space on that drive.  When I do the lvm command, it says that disk is used.  Is there any way for me to un-mount the disk or something so I can let it extend?  Or what would the best way be to start over?  I either need to extend disk1 or I need to scrap the drive because I can't lower the capacity of the VM disk now, and don't have the room (plus it would be stupid) to just add another on top of all that wasted space.