Ok - if you do choose to rehome the dog you owe it to him to do it properly.
And that means finding him a proper rescue space.
What do I mean by a proper rescue space?
The dogs are kept well- even better if they go into foster where their behaviour can be accessed, basic retaining done and matched with the right home.
The rescue provides full rescue back up - this means that if whoever your dog is adopted by can't keep them for any reason - the take the dog back
The rescue homechecks and has a rigorous process for vetting adopters.
They take a full history of the dog, with full disclosure about all its behaviours and issues and make sure potential adopters know this
Unfortunately not all rescues are really rescues. It's unregulated and there are a lot of unscrupulous people who claim to be rescues but will just take a dog and sell it to the next person that walks through the door.
Real rescues are full to bursting at the momen - because they do things properly.
Guess what they are full of? Teenage dogs, brought in lockdown that are now branded tearways. A hell of a lot of cockerpoos. It makes me... let's go with sad.
Finding your dog a good rescue space will take time, commitment and patience. Not as much as training the dog but still quite a lot. Please do that for him.
I wish, wish, wish that the "breed" had never been invented (as so does the person that invented it) because they look cute and it spawned a tsunami of evil breeders who sold them to people who had no idea what type of dog they are getting - just look cute and sound fancy.
But it's too late for that.
You might some luck with spaniel breed rescues. Spaniel Aid and UK spaniel rescue.
Please please for the love of god do not post on Facebook, gumtree or the like. You will have no way of vetting people. The unscrupulous "rescues" also trawl Facebook for free dogs, offer to rescue and them, keep the dogs in squalor or worse until they can sell them on.
Sure it's a dog not a human, but when you got the dog you took on responsibility for it.'s not the dogs fault.
All teenage dogs are a pain. Cookerpoos are know for being particularly bad. Because it's a mix of 2 working breeds and they need a job. Cockers are bred to go all day flushing out birds. They go stir crazy if they can't express their instincts.
You'd be better off with a gun dog trainer than any of the ones you've used.
I've fostered dogs like yours and there is generally nothing wrong with the dog that consistent, patient training, time, lots of time, enough exercise and mental stimulation won't fix. Plus neutering.
I'm a dog person through and through. I've had 14 fosters over the last 5 years and I've got my own lab and I'm just about really to commit to a working cocker. A dog like that is a lifestyle choice and that choice is serious training for years and years.
Cockerpoos are not for the faint hearted and are a really bad choice for first time family dogs.
But here we are.
If you are in the south east - let me know or DM me - I know a lot of the rescues and might be able to help you find a reputable one with space.