i would take a knife or something long and kinda skinny and carve out all 6 plants and all the dirt from the pot. Don't carve them out one by one or else you could strike some roots and stunt the plant. Its not going to be easy but next time a huge rule is 1 plant per pot.
When you have all the plants separated from the pot try to single each one out one at a time. Be very gentle and take your time. If it takes an hour or two, it takes an hour or two.