how do i delete something i added

Could you please clarify what you want to delete? For example, are you trying to remove a schematic component, a PCB element, or a project property? Let me know so I can assist you accurately.

I added a terminal by mistake. How can I remove it from my project?

To remove a terminal from your project you'll need to select it in the schematic and delete it. Could you please clarify which terminal you want to remove? For example, you can indicate its designator (like 5) if it's the one you added by mistake. Once specified, I can help guide you through the appropriate steps.