If you can’t send or receive friend invites, it may be because:
In order to cancel a pending outgoing friend request, you can go to your Friends list, click on the search field and type the name of the friend you'd like to remove. After finding them, click on the Cancel Request button.
You can find all your pending outgoing friend requests in Epic Games Launcher by following the next steps:
Please note that currently there is no way for you to remove all current friend requests you've sent out in one go.
If you want to delete all pending friend requests that are sent to your account, you can turn on the auto-decline mode for your Friends list. To do so, please read this article.