A client can always fire an attorney, regardless of the reason. Generally, but with exceptions, the client is also entitled to receive a copy of the file, including all filings, returns, etc.
Your question indicates that you have applied for Social Security disability benefits. While I understand that you do not want to pay a lawyer up to $5,300.00 to represent you, you should re-consider. The SS system is complicated and an experienced SS lawyer will understand the regulations and how to best present your claim. I understand your frustration, but it is best to focus on the result rather than a system that you cannot change.