/dev/root is almost full

[Processorkoeler]

Hi there!

I've installed Kali Linux on a Raspberry Pi (used the right version for that). My SD-card is 16GB in size, though Kali only recognises 7GB. I noticed this after trying a dist-upgrade, it said /dev/root does not have enough space.

This is a print of the " df -h" command:

Filesystem      Size  Used Avail Use% Mounted on
/dev/root       6.7G  6.5G     0 100% /
devtmpfs        460M     0  460M   0% /dev
tmpfs           464M     0  464M   0% /dev/shm
tmpfs           464M   13M  452M   3% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           464M     0  464M   0% /sys/fs/cgroup
/dev/mmcblk0p1   61M   22M   40M  35% /boot
tmpfs            93M  4.0K   93M   1% /run/user/109
tmpfs            93M     0   93M   0% /run/user/0

I noticed /dev/root is only 6.7G, my SD card is 16.
fdisk -l showed "/dev/mmcblk0" was also 6.7G. I expanded this to 15G.

The only issue is that /dev/root is still 6.7G and almost full.
Using this tutorial I tried to increase dev/root's size:

https://gist.github.com/vanhalt/baff...9caad40db73f50

The problem is that I cannot use the command "resize2fs /dev/mmcblk0p2".
I get the following notification:

Filesystem at /dev/mmcblk0p2 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 2
resize2fs: Permission denied to resize filesystem

I've been at this for three hours, but I don't seem to be able to successfully increase the size of /dev/root. How can I fully utulize the 16GB on this SD-card?
Apparently I cannot resize it because I'm using that partition.

I'm connected through SSH so "gparted" does not work. I can only remotely access my PI with SSH (this is a school assignment). So far I've tried everything I can imagine, but I don't seem to succeed.

Can someone please help me?
Thanks in advance.

[ksdsksd]

The resize needs to be done on a pc/Mac. A running system always has / mounted.

[fried_meatloaf]

I used gparted to resize my 32gb sd card. Try to give that a shot.