Well, I was playing my new God of War Collection (Greatest Hits edition), and when I get to the Challenge of Poseidon part, I killed all the enemies (Cerberus dogs), but the way wasn't free after I killed them, the red thing didn't disappear, then I can't continue in the game!
Please help me to solve this very sad problem (If you want I could make a video to show the problem)
The cause of force fields not coming down is most often NOT killing everything. Backtrack the way you came and check that you didn't miss an archer (they don't move) or a cerberus pup (they won't move far from where they spawned).
Oh, are you talking about the very first battle in the Challenge of Poseidon? The arena?
You may need to restart from a previous save game to see if that clears it up. You are correct that once you defeat the Cerberus (or three? I don't remember this battle all that well) and several pups, the force fields should come down. I believe you must also defeat the Cerberus via the QTE, and not just bash it's brains in until it dies.