Unlinking Epic Games

you would need to login to the ea account on ea website and unlink from there, unless they have changed it simular to epic.

Epic games changed earlier this year and locked accounts (you can unlink but only re link the xbox account with the exact same epic account)

Hi Real V.

My name is Mauro and am glad to assist you.

First you must unlink the account with EPIC GAMES but I will recommend to contact Epic games and confirm if your PS account once unlinked it can be linked with an Xbox console.

https://www.epicgames.com/help/en-US/epic-games-store-c5719341124379

Thanks,
Mauro

From Epics site:

Connect Game Progress On Xbox One to Epic Account

If you have an existing game on your Xbox One console but you haven’t created an Epic Games account online, go to Epicgames.com and click “sign in.” When the site asks whether or not you play Fortnite, you’ll select “Yes.” Choose the
Xbox icon, and a pop-up window will ask you to sign into your Xbox Live account. Once you’ve done that, fill out the Epic Games form that appears. Validate the account through the email address that you’ve provided, and the progress you’ve made on the Xbox
will now be connected to your Epic account.

Connect Game Progress On Epic Account to Xbox One Console

If you already have an Epic account for PC, iPhone or Android and want to connect your existing game progress to an Xbox One console, go to Epicgames.com and sign in to your account. Hover over your display name, and click “Account.”
Click on “Connected Account” and choose “Connect” beneath the Xbox icon. When the pop-up appears, click “Link Your Account.” Another pop-up will appear, where you’ll sign in with your Xbox Live account and confirm the connection.

You can link Epic games across multiple platforms and consoles through an Epic account, including the Nintendo Switch, Playstation 4, Twitch and Github using the same process above and selecting the appropriate platform or console when
prompted. This will allow you to share game progress, stats, upgrades and loot across all platforms through one account.

you need to log into your epic account to unlink it from your xbox account. go in your settings on epic and it should say linked accounts go to that n select unlink.

hope it helps

The error on Epic game might be happening due to you having unlinked your Microsoft Account.

Do you have your Epic Account login information?