[Homeoboxter]

Yep, those connectors can be separated using conventional wrenches, but if it's really stubborn and won't budge, better not force it and just get a flare nut wrench set that fits around the whole thing and gives you a better grip:

https://www.amazon.com/DURATECH-3-piece-Vanadium-Organizer-Included/dp/B08FB2N8V6/ref=asc_df_B08FB2N8V6/?tag=hyprod-20&linkCode=df0&hvadid=693284521083&hvpos=&hvnetw=g&hvrand=14307591880238943829&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9031970&hvtargid=pla-1063072767822&mcid=988005e1162a398cb834801b8b861a51&th=1