I recently submitted a request through Riot support to change the name for my account so that I did not have to type or see my current one to log in or have to see it in the account details.
Unfortunately, the support team, while kind and professional, was unable to help me because it was not technically possible. I find it unacceptable that this is not possible. There are many reasons someone would want to change not just their summoner name. Personally, mine now makes me uncomfortable and triggers dysphoria.
No other game, platform, or social media seems to function this way, Even Valve will change your Steam account name if you make an appropriate support request.
Riot needs to do the work behind the scenes for account infrastructure to make this possible. Or, in some way make the tools available for their support teams to resolve these types of issues instead of in effect saying "sorry you're out of luck".
My support team member told me Riot devs might just pay attention If I called attention to the issue here on the boards.