Can’t open MacBook Air because is asking for iCloud password to log in and I don’t remember

Start from the beginning. First, please follow the steps in If you forgot your Mac login password - Apple Support.

If necessary, proceed with If you can't reset your Mac login password - Apple Support. Stop upon reaching If you still can't reset your password, erase your Mac.

That brings us to your original question. Assuming you have been unsuccessful thus far, proceed with If you forgot your Apple ID password - Apple Support, and return to the beginning to determine if you use those credentials to log in to your Mac.

If you remain unsuccessful, review all the account recovery options described in How to use account recovery when you can’t reset your Apple ID password - Apple Support. If you don't want to do that, you can always return to the previous document and follow the instructions to erase your Mac.