As a non-native speaker, it's funny to me that some people think they don't have an accent. An accent is just the way you talk, if you speak, you have an accent.
What everyone seems to think an accent is, is "this person has a different accent from mine, therefore they have an accent".
It's like seeing a blond person for the first time in your life and saying "it never occurred to me I had a hair color".
We say it in Western Massachusetts, but it's clipped, more like "Can I help yal?"
“Ya’ll” is linguistically necessary in English since the word “ye” was deprecated.
A common alternative to remove ambiguity between singular and plural “you” in some parts of the US is “you guys”.
Ye is a second-person, plural, personal pronoun (nominative), spelled in Old English as "ge". [0]
The word thou is a second-person singular pronoun in English. It is now largely archaic, having been replaced in most contexts by the word you. [1]
We deprecated ye and thou, but it’s the latter that “requires” y’all, because only thou (relative to us still having you) distinguishes the number of people.
Edit: put another way, “thou/thee is the one with number” meant that reintroducing them would create a number distinction.
that said, i wouldn't even worry about your accent. oftentimes, it's a great piece of conversation fodder, and a connection to your past that you take with you where ever you go.
A relative grew up in Minnesota but moved to Dallas as a young adult and ended up with a mixture — now there was an accent! (The MN part is now more or less gone.)
I deliberately trained myself to speak with a neutral American accent - probably what you mean by a West Coast accent - by watching particular actors and practicing - in private - speaking like them. In particular, for me, it was John Malkovich, who has perfect diction and enunciation.
This was in my teens and it took a couple of years, but it paid off. Nobody can tell where I'm from now, though people mostly assume California. I still say "y'all" but I say it with no Texan drawl, which sounds a bit odd to people, I think.
Just find people who speak the way you want to speak and watch them, listen to them, try to repeat things they say until you've got the accent down. At first it'll seem embarrassing, even if you're alone, and you'll find yourself feeling like a pretentious poseur for a while, but eventually you won't. It'll just be how you speak English.