When you need to format a partition from the command line, a few commands are all you need. Here’s the typical workflow.
First, create the filesystem:
mkfs.ext4 /dev/sdxy
If you want to reserve less space for the root user:
tune2fs -m 0 /dev/sdxy
Check the filesystem for errors before mounting:
fsck.ext4 -fy /dev/sdxy
Then mount it where you need it:
mount /dev/sdxy /wherever/I/want
Replace /dev/sdxy with your actual partition and /wherever/I/want with your mount point.
Enjoy!