My account is still visible even after the deactivation.

Even if you have deleted your account, it may take some time for your account information to delete entirely from the League of Legends official API. 

Once your account information is gone from the League of Legends official API, it'll no longer be visible, and your account will only appear as a 'del#number' or 'random number' on other summoners' pages. 

OP.GG does not delete or modify all summoner information.