Born American Canadian recently harassed by Homeland Security

But it is you pricks who wish me ill that are really sick in the head.

I don't wish you ill, I just want you to not be American. Please renounce your US citizenship. It's embarassing to my country that you can call yourself a citizen.

But it is you pricks who wish me ill that are really sick in the head.

No one wishes you ill. That's all in your own head. We think you're the joke that never ends and has no punch line.

On the tax question, fleshing out what I've already said, since it seems not to have sunk in:

It is probably the case that you would not have owed any US taxes if you had been filing US tax returns, on account of the tax treaty.

But we don't know whether non-filers can avail themselves of the benefits of the treaty. The treaty doesn't exempt you from filing. (I haven't looked at the treaty, but no treaty exempts people from filing; it wouldn't make sense.)

So it may be that, because you haven't filed, you cannot avail yourself of the benefits of the treaty. If that's the case, then you owe back taxes. The statute of limitations for US income tax is ordinarily three years from the due date of the return or the date filed (whichever is later), but that only applies to people who filed returns. There is no statute of limitations for non-filers, so conceivably you owe back taxes for the last 40 years or so.

If that's the case, it would be hard to convince the US taxing authorities that your renunciation was not tax-motivated, and there would therefore be tax consequences to a renunciation.

You need to talk to a lawyer before renouncing.