How to delete a system after creation?

Is there anyway I can remove a test system I created?

If you designated it as a test system before you started, then yes, you can remove it completely.

Otherwise, you can "Kill" it, and it becomes less easy to find, but some record of it remains publicly viewable. This prevents the "gaming" of the C2 site by those who create 100 test systems, and then kill the 98 that happen to not work.