If you ever wanted to resize a partition to grow unfilled space, you can use parted to grow the partition size.

parted /dev/sdx

or

parted /dev/mmcblk0

print

Now note the size of the disk and the start of the partition that you want to resize.

rm n=partition that you want to delete mkpart

Partition Type ? primary/extended ? primary Filesystem type? [ext2]? ext4 start ? startSizeMb/GB End? endSizeMb/GB quit reboot (may not be necessary) resize2fs /dev/sdx