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Windows OS residing in /dev/sda5 in the figure you've shown. In your system it's the only ntfs partition large enough to hold windows installation.

You can easily mount and see which partition containing what and decide to remove them. Like in Windows installation partition you'll find folders relevant to windows. To mount ntfs file system in Linux you need ntfs-3g driver, which usually comes inbuilt with Ubuntu. Otherwise install it using apt install ntfs-3g.

In your system /dev/sda1 is mounted as /boot/efi. So, it's containing grub boot loader. So, don't delete it even by mistake. You can delete /dev/sda2-/dev/sda5 and sda6, sda7.

If your main purpose is freeing up disk space I'll suggest you to delete /dev/sda5 only. Other partitions mentioned above has windows recovery, Windows bootloader etc. They may be helpful in case of a factory restore etc.

Always have a backup of all necessary files before deleting anything.