Step 1:

- go to the "library" tab, find "Marvel Rivals" and click on it;

Step 2:

- under "play", click on the "support" topic;

Step 3:

- under the listed issues, click on "I want to permanently remove this game from my account";

Step 4:

- click on "ok, remove the listed games from my account permanently" and confirm it;

Step 5:

- never come back.

thanks for reading this guide and I hope it helps!