If you want to delete physical disk, but it have filesystem and not visible from GUI.
You can get error:
OVMRU_002026E Cannot use or delete physical disk: FreeBSD (1), it already contains a file system:
[0004fb0000050000b4ed2daa9d83c7a8].
Solution:
1. Connect to OVM CLI
[root@ovm]# ssh -l admin localhost -p 10000
2. Delete filesystem
OVM> delete FileSystem id=0004fb0000050000b4ed2daa9d83c7a8
