To remove one of your game accounts, you go to the left sidebar navigation where your Games appear
Click on the game you would like to change/remove your Game Account of.
Then click on the account you wish to edit/remove as seen in the following picture
For the next and final step click on the 3 dots (...) and remove your game account.
Please note: If you have any kind of ongoing activity, even if you are only in the team finder and no tournament or ladder, you cannot remove your game account.
Double-check that you don't have any ongoing activities before trying to remove a game account. After the account has been removed you can add a new one.
Note: You can only have one account for each game. For League of Legends you can have one account connected for each Region.
Running into other issues, or do you have additional questions? Feel free to chat with us by clicking (?) on Challengermode.