Chosen Solution

So i want to reinstall my mac but when i choose the disk apple asked me for the apple id to sign in to apple store, but the problem is that i don’t remeber my first apple id. Is there another way to make this reistall or to enter the another id? I would like to point out that I can’t do restart with a startup disk :)

Here’s what to do if you forgot your Apple ID: https://support.apple.com/en-us/HT201354