Remove pass-through Disk

hello,
I m trying to help out a friend. They have migrated their server 2008 to server 2012.
When try to create a snapshot they get an error where basically it states, that it cannot take snapshot because one or more pass-through disks are attached.

so my question is how do you remove the pass through disks ?

Please remember to simplify the answer as I an not well versed with the 2012 server.

thanks in advance.