Yep, you can delete your Windows partition once you no longer need it or any data within it. Then once you update your bootloader (usually GRUB, some distros do this automatically when updating the system), Windows will disappear from the boot options.

Then you can either create a new partition in its place to store data on, or extend an existing partition to fill the empty space.

I’d recommend also backing your data as a precaution in case something goes awry.