Changed my username and my data is gone

Greetings! I changed my username in the official Minecraft website, and I'm using the official launcher. So I have a question regarding the steps Roman sent. He sent these following steps:

• Take a backup on the backups page

• Download the world

• Find out your UUID

• Rename your old UUID with the new UUID

• And upload the world

So once I make a backup and download the world, what happens to the original world, do I have to delete it? I'm confused

Thanks!

Ah got it thanks, you can close the thread

Cracked is enabled