my chatroom It was never in use the question was solved before
I do not want to leave my trash behind
Don't worry about it. Inactive rooms are deleted automatically by the system. I don't remember if non-mods can delete the rooms they created, but if you can, it will be on the "Access" tab.
So, try going to https://chat.stackexchange.com/rooms, find your room, click on the "info" link of the room, go to "access" and see if you have a delete button. If you do, great. If not, never mind it will be deleted in a few days anyway.
Related post on Meta SE: How do you delete a room on chat?
Related chat FAQ: Will these rooms exist forever?
Quote (emphasis mine):
Rooms will exist indefinitely, so long as there is at least one person actively talking in the room. A room is considered worth retaining if it has more than 15 messages by at least 2 users.
Rooms not worth retaining which are inactive for 7 days will be deleted. Rooms worth retaining which are inactive for 14 days will be frozen. Frozen rooms do not allow any new messages to be sent, and are not shown in the default room list to prevent cluttering the rooms interface.
TL;DR: Post nothing and it will be cleaned up automatically in a week.
(terdon already deleted this one manually though, as mentioned in his own answer)