Definitely tell staff what happened. I wouldn't risk not saying anything.
I've made an Alt account without permission

they won’t care as long as u don’t cause trouble
And what do you refer from the word "trouble" loll

they won’t care as long as u don’t cause trouble
And what do you refer from the word "trouble" loll
Probably using the account to do anything bad that would get your account closed, but since it's an alt, you wouldn't care.

Hello @A-ARUSH
Here you'll find all information needed for using and authorizing an alternate account:
https://support.chess.com/article/596-can-i-have-multiple-accounts
I've made a alt account with any other email adress but with same device without the permission of any chess.com staff because i didn't know that i have to ask permission first. I made that account for chess practice. Should i close that account or ask staff about that. I'm just scared they don't close my main account for my activity