1. Delete Journal records:

journalctl --disk-usage
sudo journalctl --rotate
sudo journalctl --vacuum-time=2days
sudo journalctl --vacuum-size=100M
sudo journalctl --vacuum-files=5
sudo -H gedit /etc/systemd/journald.conf
systemctl daemon-reload

2. Check for heavy files and then clean:

sudo du -a / 2>/dev/null | sort -n -r | head -n 20
sudo apt-get autoremove
sudo du -sh /var/cache/apt
sudo apt-get autoclean
sudo find / -xdev -type f -size +100M //Command to check files greater than 100MB.
SET GLOBAL binlog_expire_logs_seconds = 3;  //Command in Mysql 
expire-logs-days=3
PURGE BINARY LOGS TO 'binlog.000113';  //Command in Mysql

3. Create an automated Script in /var/www folder and name it as cleanup.sh:

#!/bin/bash

# Log rotation and cleaning journal logs
echo "Rotating journal logs..."
sudo journalctl --rotate

echo "Vacuuming journal logs older than 2 days..."
sudo journalctl --vacuum-time=2days

echo "Vacuuming journal logs to limit size to 100MB..."
sudo journalctl --vacuum-size=50M

# Remove unnecessary packages
echo "Removing unnecessary packages..."
sudo apt-get autoremove -y

# Clean package cache
echo "Cleaning up package cache..."
sudo apt-get autoclean

# Check disk usage of cached apt packages
echo "Checking apt cache size..."
sudo du -sh /var/cache/apt

# Finding and deleting large .bin files in MySQL directory
echo "Finding and deleting .bin files larger than 50MB in MySQL folder..."
sudo find /var/lib/mysql -xdev -type f -name "*.bin" -size +50M -delete

# Clean Docker (if Docker is installed)
if [ -x "$(command -v docker)" ]; then
    echo "Cleaning up Docker system..."
    sudo docker system prune --volumes -f
else
    echo "Docker is not installed, skipping Docker cleanup."
fi

echo "Cleanup complete!"

After this, run following commands:

chmod +x /var/www/cleanup.sh
export EDITOR=nano
crontab -e

0 0 * * * /var/www/cleanup.sh >> /var/log/cleanup.log 2>&1

crontab -l

TO manually run this,
1. cd /var/www/
2. sudo ./cleanup.sh