Free up SD Card storage

Hi all,
I am struggling to free up storage space on my 32GB SD Card. I am running HASSIO on an RPi4.


I followed the official guide to clean up storage space but it was not much of a help. I even cleaned up the unused docker images using Portainer addon.
Firstly I am not a Linux guy but I love to tinker around and found the below commands:

Command 1:

du -h -d1

Here I could see only 6.6GB of the space is being used.

Command 2

df -h

I can see some mounted partition eating up my space. Can anybody suggest any solution as to how I can get some of the free space back?