Forget email apple id

1. If you've forgotten your Apple ID email please take a look at If you've forgotten your Apple ID – Apple Support for help.
2. Activation Lock for iPhone, iPad and iPod touch – Apple Support - To fix Activation Lock you'll need to follow steps at the aforementioned link, you will need to be the original owner of the device (You might need to submit your purchase receipt/invoice to Apple), if you are not the original owner, you'll need to get in touch with whoever you bought the phone from and ask for assistance.

I already posted these answers to your questions in your other post. There is NO WAY to open Activation Lock without the Apple ID and Password of the original owner unless you are the original owner and can produce the original receipt clearly showing the serial number of the device!

It’s unusual to forget your email address, but Apple has some suggestions on how to remember it. See→If you forgot your Apple ID - Apple Support