Retired VS non-retired tax reporting

I retired from a local government in 2020 and receiving regular pension.  As I  have several licenses that were hard earned and I have no intention of giving them up, but they do cost me to keep them every two to three years as I need to renew and  take some continue education to keep them.  Can I just changed my reporting status s back to  Civil Engineer like I am still working without a W2 form to report? 

Also if I keep that, would  I be able to deduct some expenses like buy a new PC etc?  Also can I work on simple project without getting a business license?