removing next of kin?

I would be surprised if this was possible as family is still family. Ultimately the first question is - if your family are not to be your next-of-kin, then who is?

If you have someone in mind (a partner or close friend), then I am sure you could make a formal legal document assigning them as your formal "next-of-kin" in the event that you're incapacitated. While there would no doubt be disagreements about it around your hospital bed, a formal legal document will very quickly end those disagreements.

You can also make a will formally expressing what you want to happen to your possesions in the event of your death - since you have no wife or children (presumably) then you have no obligation to leave anything to your family. If you die without a will, your possessions automatically pass back to your parents.

Outside of death or serious injury, the concept of "next-of-kin" is largely irrelevant, but if you're really serious about it, no harm to speak to a solicitor about getting formal declarations/affidavits drawn up.

It's an interesting one alright; clearly there's no official register of "next of kin". The Gardai most likely check their own records or contact the HSE, perhaps.

Basic things you can do are to keep a card in your wallet listing the names of those you would consider your next of kin, and a number in your phone titled "ICE" or "In case of Emergency".

Outside of that, maybe contact the HSE - somewhere there's a record with your PPSN, family details and medical details. I imagine it's possible to specify an emergency contact in that record?

There's also an emergency services forum here with plenty of Gardai, firemen and paramedics posting - maybe ask there how they find out who a person's next-of-kin is?

You're young, so as you say you don't have much to your name, but it never hurts to make a plan. The few hundred euro in your bank account could make a big difference to a charity or a good friend. Employers often also have in-employment death benefit schemes - enquire with your HR department about updating the person who will receive any money in the event of your death.