Format linux pendrive

# Identify USB drive in your system
df -h

# Linux can't format devices that are mounted. Unmoute using
sudo umount /dev/sdc1 

# Format with file system
# use any of
sudo mkfs.vfat /dev/sdc1 
sudo mkfs.ntfs /dev/sdc1 
sudo mkfs.ext4 /dev/sdc1 
Worried Walrus