Seeing as non-subsribers are only allowed 2 pending maps (while having 0 ranked maps) there are a few things you can do. Remember that with every ranked map you have your pending limit goes up by 1 (5 max for non-subscribers).
- Wait a month for 1 of them to graveyard automatically (with no posts or updates on it) and you will be able to upload another one - Get one of the maps Ranked (that will open up 2 slots for you as your pending limit will go up) - Become a subscriber and get another pending slot (3 with no ranked maps)
The main choice is to try and get your maps ranked, the limit is there to stop people uploading a bunch of maps and never working on them. The submission section on the FAQ explains all of this as well