How do I get undiagnosed with Asperger's?

I did a quick Google search and found that apparently in 2017 there were 231 regular serving personnel and 32 reservists in the UK armed forces who had an autism or Asperger's diagnosis on their medical record. Additionally in 2018 the military updated its standards to allow for more discretion on a case-by-case basis concerning certain medical conditions. In other words an Asperger's diagnosis doesn't outright bar you from military service and they can assess you on a case-by-case basis instead.

When you apply to join the army if they query your diagnosis you can explain that you believe you may have been misdiagnosed and that regardless the diagnosis will not affect your capacity to serve. Ask them to assess you on the basis of your individual capabilities instead.

I would think the only way really rectify a diagnosis is to get reassessed (unless you think that the old diagnosis was just a pure clerical error or something, in which case you could simply ask them to correct your medical records). They will not usually remove a diagnosis from your medical record at request; at most they would amend it to state that you disagree with the diagnosis.

To get reassessed via the NHS you would make a GP appointment and explain to your doctor that you think you may have been misdiagnosed and that you would like a referral to be reassessed by an autism service (e.g. the Leeds Autism Diagnostic Service).

The autism services tend to be overstretched and have a long wait list. Therefore they may be somewhat hesitant to refer you when you already have a diagnosis. If that is the case I would recommend telling your GP (as well as the autism service) that the main reason you want the reassessment is that you are applying to join the military and that you would prefer clarity on your diagnosis before you proceed with your application. That may persuade them. Alternatively they may just suggest that you simply try proceeding with your military application and leave it to the army's medical assessments to work out.

If the reassessment says you don't have Asperger's/ASD, they can amend your medical records to reflect the outcome of the reassessment and clarify that they think you were either incorrectly diagnosed previously or simply that you no longer meet the criteria to diagnose ASD. 

If the reassessment says you do have Asperger's/ASD, there are a couple of things they may still be able to do to help you. Firstly they may be able to write a letter clarifying that your diagnosis should not affect your capacity to serve (I'm not sure how much it will help as the military medical folk might have their own ideas, but it's worth a shot). Secondly they may be able to help you deal with the embarrassment and stigma.

However it turns out I wish you the best with it.

Helpful answer, thanks. Interesting that they now let some people with it join up. I thought that it'd be a long and difficult process so I'm not surprised by what you told me, but still I think I'll give it a try. Hopefully the fact that they were saying that I might not have it (I was only young so don't remember much, but they were at one point saying that I probably didn't have it, although the diagnosis remained unchanged) will help my case.

Helpful answer, thanks. Interesting that they now let some people with it join up. I thought that it'd be a long and difficult process so I'm not surprised by what you told me, but still I think I'll give it a try. Hopefully the fact that they were saying that I might not have it (I was only young so don't remember much, but they were at one point saying that I probably didn't have it, although the diagnosis remained unchanged) will help my case.