Help. Termination of a contract

[#1]

Hello, I would appreciate a guidance regarding my case, a few weeks ago a client contacted me directly by Upwork chat to do a project, which was established as a fixed price, in the end the project was not satisfactory for the client so we decided to make the termination of the contract, but the client has not yet completed it and I do not know if I do it or how it would affect me to do so, also if I end the contract the blocked money will be returned to the customer? Although the work did not meet the client's expectations, he was very kind and we were on good terms, so I would not want to affect him either.

Another point is that until tomorrow the customer has the opportunity to take action on the contract, otherwise the money will be released to my account.