I can delete my account from another Nintendo switch. What should I do?

Hey guys hope you can help me there.

I borrowed my account from a buddy on December. I have no more contact with him and can no longer reach him.

Wanted to play Switch for a long time, I bought a new one before I sold a Switch, unfortunately stupidly, didn't really think about it. In any case, I bought a new switch and have the problem that I can only play the digital games that I bought in the eshop online, not offline. I'm trying to set my console as the main one, unfortunately, because the switch is now active as the main console on a buddy. I've already changed my password, in general, he doesn't have to go to the shop himself. Nevertheless, I don't know how I can set my switch as the main one without problems?

Does anyone have an idea?

If none of this makes any sense, I call Nintendo support so that it is no longer on my account. From my point of view, that was the stupidest thing I've ever done.

I'm very sorry right now…

Sell your nintendo switch