Welcome, @Joe_Porto,
Some of my Asana workspaces still have Profile image > More > Remove me … so that still works sometimes (as @Bastien_Siebman noted).
But in other cases, including yours, where the above isn’t present, try this instead: Profile image > My settings > Account > scroll all the way to the bottom > Click Remove me … link at the far right after confirming you’re in the org/workspace you want to be removed from.
Thanks,
Larry