I agree with the above poster about possibly coming up with an alternative plan, so that when you tell them it wont just be like "I'm not doing this, so Im going to be wandering around la la la" because of course, parents reaction is to worry about you, out of concern and what not.
It is possible to look at your current level of training as good experience, a good use of your time because you found out some things you are good at, but also found out that it is not an area you want to pursue further. This makes room for you to try something more suited to you and your skills, which is good!
If you keep it positive when you present the idea, maybe they will be able to handle it better.
Good luck and let us know how it goes
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Your Aspie score: 165 of 200
Your neurotypical (non-autistic) score: 48 of 200
EQ 12 SQ 70 = Extreme Systemizer