There are some areas that I'd be excited to use, but there isn't a practical way to get in.
1) Tree Gnome Stronghold - I haven't attempted to use the Spirit Tree in the Tree Gnome Village, so I'm not sure if it functions or not. But it would be nice to remove the gate (or fix it?). Coords: 2459, 3383
2) Arandar - I never explored the Tirannwn region when I played RS way back when, so I'm curious what's there. The gate does not work. Coords: 2384, 3334
Feel free to add other door removal suggestions in the comments if there are other significant ones that could use a quick fix.