Newbie Question: Remove Planter Box

I just got this game as it looked interesting and I very much enjoy Terraria & Starbound and it seems not too bad so far. As the title suggests though, I'm at the starter quests and at the one where it wants you to craft a planter box and build seeds. Now, like an idiot I hovered over a not great area, clicked by accident and since nothing appeared to change I didn't think anything had happened. So I cleared up the area better and when I went to place the planter box again it says I can only place one and I am unable to plant any seeds in the area I accidentally placed it previously. Is there any way for me to remove this or am I just going to have to quickly start again since I'm not really that far anyway>