As they mentioned above, the exports folder.
The only maps inside cape are custom ones that you or other users made, that we can agree on easily.
Now the things is if you make tons of maps yourself, this also fills out portals.
Remember that not only exported maps in the exportsfolder gives you a portal, but also, if you made a map from within the map maker, checked "Has portal" and then saved it, the map folder works as an actual map.
So if you created maps yourself and gave them a portal, these also has their own portal in cape, not to mention that if you export these later on, and doesn't remove the exported file for them inside the exports folder, you will have 2 identical map portals inside cape.
C:\FeralHeart\media\terrains
&
C:\FeralHeart\exports
Works the same way, the only thing is that the exports folder holds exported and encrypted files, the terrains holds the whole map folder that's easy to edit.
These two places are the only ones you can delete these cape portals from.
Also make sure you restart the game after deleting these portals or otherwise they still might be there.