Alberto:
Clients can end a contract AT ANY TIME.
For ANY REASON.
You don't need to get permission from Upwork.
You don't need to get permission from the freelancer.
It sounds to me like working with this freelancer is just a waste of your time.
If you REALLY want to end things immediately, then just use the tool the way that is intended to be used.
Find the contract, and use the "three dots" icon to show the dropdown menu, and choose the option to "close" or "end" the contract. Release any remaining funds in escrow to the freelancer, and you're done.
But maybe you DON'T REALLY want to end things as quickly as possible. You said you don't want to pay.
Wanting to "not pay" and wanting to "end things immediately" are two different things.
If you want to not pay anything, then you need to get permission from the freelancer, because you funded an ecrow payment that is intended to be released to her.
You CAN edit the amount of money to be released, and change it to ZERO, and then click the button, and that will send the freelancer a request for a refund.
She may agree with your request. Or she might NOT agree. If she doesn't agree, then a dispute will be created. That means that an Upwork mediator will encourage you and the freelancer to work out your differences.
If the two of you can't come to an agreement, then the next step would be arbitration. In order to go to arbitration, then the freelancer, the client, and Upwork itself all pay $297 each (non-refundable). And an abritrator would make a binding determination about who gets the escrow money. If you agree to go to arbitration, but the freelancer does not agree to do so, then you will win the money and nobody pays for arbitration. If the freelancer agrees to go to arbitration and the client does not, then the freelancer receives the escrow money.
So there are steps involved, and none of this is how Upwork actually wants contracts to go.
From a business perspective, the best thing for you to do would probably be to just end things immediately. Don't spend more time on this freelancer.
If you're not willing to do that, then I recommend you TALK to the freelancer and see if you can come to an agreement. Tell her briefly that you have decided to go a different direction, and you would like to end the contract. Ask her if she would be willing to accept 50% of the money in escrow. (Or 20%. Or zero. Or whatever offer you want to make.) Point out that you would be grateful for her flexibility in this manner. Point out that if she agrees, then she won't need to do any more work on the project. If you ASK her first, then it is more likely she will agree and this thing won't go to the dispute stage.
