I am a great fan of Zorin and I think I have installed it multiple times without deleting the previous versions? Could that be possible? Please watch print screen over here: Screenshot by Lightshot
What else could it be on sda1 and sda2? Can I delete these partitions to save space?
I sometimes get Busybox initramfs error and I think it might be happening because of not enough space?
I am not a pro, so these are just newbie suggestions :).
Those are /Boot partitions and removing them would render your OS unable to boot. If you removed them, you would have to recreate those partitions, then repair grub.
They also are taking up very little space.
You can launch the Disk Analayzer from the app menu. Select a drive to analyze. It can take a couple minutes.
That will give you a good idea of what is hogging space.