how do you delete data on online games

is there a way too just remove anything that I did on that game and save every other games data and restart my account from the start

You Only need delete the Epic Account? If you know the Epic Account Data with you have you can go and access your epic account and Unlink with your Live account

I tried but I won't let me sign in

I say that I have already used the game before and if I can use my Xbox account email and password but it says that no fortnite account is on it but when I go to link my account to Xbox live, it says that there is an account that is already signed in

Hello Ompatel,

Thanks for coming to the forums. We understand want to delete your online data? From the console you can go to my games and apps>highlight the game> hit start button go to manage game and add on. Then find the save data and hit A, two options will come up
delete from console or delete from everywhere. You will want to select delete from everywhere to delete from console and cloud. However with Fortnite there is data that is saved on the server side. Unfortunately, there is no way of deleting that.

Thanks,

Brad