Greetings!

Hope you're doing great.

I'm not sure if there is any process where you can change the reserved category after submitting general as a final. In the application process itself it's mentioned that no changes will be made once you submit the application. However, there are editing window which opens after submitting the form, do check out if that can be changed during that period. Whichever, management exam you've applied for, contact the concern examination body in case this rectification can be made.

If the case was reverse then, you could have easily converted to the general category in case you were unable to submit the latest caste certificate. I'm not sure if that can be done in the reverse process. 

Hope this will help. Do reach out in the comment section if you need any help.

Cheers!