Login as the root user and run the command
Select Index => Partition => the disk to edit with arrow keys and SPACE.
To use the entire disk for FreeBSD, select A.
Answer YES for the question: Do you want to do this with a true partition entry so as to remain cooperative with any future possible operating systems on the drive(s)?
For the install the boot manager question, select None with SPACE then hit ENTER for OK.
Quit the FDISK Editor.
You will be again asked about the boot manager, select None again.
Select Label from the Index menu and Label as desired. For a single partition, accept the default size, type filesystem, and a mountpoint (which is not used).
The filesystem will be newfs’d for you, unless you select otherwise You will get an mounting error. Ignore it.
Exit out by repeatedly pressing the ESCAPE key.
The new disk is now ready for use.