Hi, Villager!
Thanks for reaching out to the FAQs! ;)
We understand your frustration when you lose diamonds for an accidental purchase.
We are always doing our best to help users and we would like to further assist you by removing the items and giving you the diamonds back, but, unfortunately, we are not able to remove items from your account.
This would leave it with adverse effects and you would not be able to play normally again.
Feel free to contact us via in-game support, if there's any further doubts.
Kind Regards,
Team Block Craft