You need to understand that removing a package that was included in the originally flashed firmware does NOT free any space. The original firmware and all its packages stay intact. You can only remove those packages that you have installed afterwards.
The file system consists of a read-only firmware squashfs + a read-write jffs2 partition where all your changes get stored (ubifs for some modern routers). When you try removing a pre-installed package, you actually just hide that via a hide mark (in the read-wrote partition) and consume a little bit more disk space (as the original package binaries stay in the read-only part).
As the original firmware is intact, the easiest thing for you is probably to reset the router to the clean flash situation. Just issue the command "firstboot" (or just press that "Perform reset" button) and that should remove all your package changes and config change, leaving the router as if it would have just been flashed. Then reboot and you should be fine.