Here is very simple bash command to format partition, mkfs.

Format will erase all of your data. Please be careful to run.

My example, I format partition with ext4 file system.

Syntax

-t : describe specific FILESYSTEM

-V : show detail

Command,

$ sudo mkfs -V -t ext4 /dev/sdc1

Now my partition has changed from NTFS to ext4.

Check partition with fdisk again.

$ sudo fdisk -l