Drive Full and Cannot Login - How can i delete some files via terminal so i can regain access?

Is there a way i can delete some files via the terminal and what are the steps to do so?

We uploaded more files that the root drive can take by mistake and now drive is at 100%. So I assume new sessions are not able to generate because of this. Is there a way I can clear some space to regain access?

Filesystem 1K-blocks Used Available Use% Mounted on
udev 8117136 0 8117136 0% /dev
tmpfs 1629716 1180 1628536 1% /run
/dev/sda2 114336932 108501956 0 100% /
tmpfs 8148560 0 8148560 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 8148560 0 8148560 0% /sys/fs/cgroup
/dev/loop1 93568 93568 0 100% /snap/core/8689
/dev/loop0 96128 96128 0 100% /snap/core/8935
/dev/sda1 523248 6152 517096 2% /boot/efi
tmpfs 1629712 0 1629712 0% /run/user/1000

You can delete files in data/username/files. You must make a scan with occ perhaps before or past login.

How can change permissions or allow my root user to get in? Because i am unable to view folders in that directory.

Directory /var/www/html/nextcloud/data: permission denied

You can access it as root, or as the account your web server uses.