How do I Un-Train my dog?

It sounds like you've got the right instincts - give her praise, treats, and affection while she's on the couch to encourage a positive association with it. I'd try changing your approach just slightly. Ask her if she wants to come up, rather than asking her to come up. It's a subtle change (and one that is more for your benefit than hers), and the only real difference is that you want her to make the choice rather than just follow the command. Essentially, there are things we want our dogs to do when we ask, all the time, no matter what, like "leave it" or "come." These are non-optional. But there are plenty of things we ask our dogs to do that can be optional. If it's not contributing to their health and safety, it can be optional. Stating these as non-optional (commands) primes you to follow through if she doesn't respond, but if you ask it in a way that makes it her choice (questions), then you're preparing yourself to shrug and move on if she tells you no, thanks. If you give her the choice, she knows she's in control of the situation and she is free to leave with no consequences whenever she'd like. Then when she's up there, give her treats she can't take somewhere else to enjoy, like small pieces of something she loves, canned food/peanut butter in a syringe, etc. She can have it so long as she's up there, but the treats stop when she goes somewhere else. Nothing bad happens if she leaves, but the treats only appear in proximity to the couch. If she has a bed or mat she's comfortable on, you can try moving it to the couch to help make the spot more appealing and feel more like hers.

I might try to get a special blanket and call it her 'bed' so you can invite her up onto the couch on her bed, by saying 'Come on your bed!' or some kind of other key word she can associate the special blanket with.

I second the other two answers. Keep up the praise, give treats, and just relax, and give it time. Also, don't push the issue. She wants to please you, but is obviously confused. Just chill, don't add any pressure, and allow her to do what makes her comfortable.

Teach your dog the place command. Then work on duration. After they know a command then start correcting for breaking it. Once she knows place, put her in place next to you.