I tried /prop osall 1 in my localhost server, didn't work. I also tried /prop SetOpenState 1, didn't work. I also tried /unlockmap, unlocked the map but did not remove borders. Surprisingly couldn't find this with the search function. It's been a while since I've done localhost and it seems like all the configuration and configs and commands and plugins are always changing so I don't know what's going to work with my current resources...
Solved, do /prop setopenstate 48 to remove map borders.