Please note that disconnecting your platform from your Epic Games Account can affect your game experience:
Any game progress stored on a disconnected account will not be accessible by your other linked accounts.
You also won’t be able to connect a different platform of the same type to the same Epic Games Account. For example, if you disconnect your Xbox account, you won't be able to add a different Xbox account to the same Epic Games Account.
If you sign in to your Epic Games Account using the platform that was disconnected, you will automatically create a new Epic Games Account. This new account will not have any game progression.
If you still want to proceed, follow these steps:
Visit your Epic Games Account Portal
Select Apps and Accounts on the left
Click the Remove button below the platform you want to disconnect