Just stop. The end.

No need to explain why you didn't do something, and honestly, most people don't even care why.

Just apologize, sincerely, and move on.

This isn't an ADHD issue, it's a maturing thing. Many people rationalize their mistakes while apologizing, which just devalues the apology.

Own the mistake, apologize for it, and move on. By doing this, you show respect and consideration for those you've affected, while also freeing yourself from the justification/rationalization feedback loop in your head.

I read a book, "Courage to be disliked".

I am too lazy to type out how it relates to your question, but give it a shot.

I don't make excuses anymore. It's very tiring and I prefer to just face the consequences. People seem to respect me more because of it.

For me it helped to address why I made them in the first place. When I was younger (and now), the real reason was always that my executive function just needed more cooldown time or at least a different sort of activity than the one that I was lying about. That wasn't language I had access to at the time. The closest thing I had was "I can't", which adults never let me say because it was always in relation to things they'd seen me do before, so they couldn't fathom that I couldn't do it then. So I had to make something up. But in my current adult life, actually, people recognize what my struggles are and understand if I just say what really did happen (executive function misfire). Or if I don't know them that well I just say something personal came up, which is what an executive function misfire is, no lie, they just aren't privy to stuff that personal.

You can also amend something you've just said. "oh I'm like almost done with that project" (pause for a beat, realize that's a lie) "ok thinking about it for a second, more like half done."

Work on saying the truth the first time, but in the interim don't double down.

Try, "I have no excuse," and only explain when prompted. You may desire to be heard, but you can explain yourself after the apologies have concluded.