Remove a not finalized datapack

As long as you didn't finalize the armor stand creation datapack, you can simply remove all armor stands with the "Restore object" option from the datapack book.

Remove a finalized datapack

If you finalized the armor stand creation, there's an option to remove entities summoned by our datapacks within the book.

If you don't have the book anymore, you can use the Minecraft /kill command.

Be careful with the /kill command! If used wrong, it can delete every entity on your map!

Make sure you follow those rules:

1. Backup your Minecraft world! Edits with the Minecraft /kill command cannot be undone!
2. Use /minecraft:kill instead of /kill if you are on a server!
3. Always limit the command to armor stands within a certain distance!
4. Armor stand creations from this website are tagged with "www.minecraft-heads.com", so you can also limit the kill command to entities with this tag.

/kill @e[type=minecraft:armor_stand,distance=..5,tag=www.minecraft-heads.com]