I have a iPhone I found

When you say you found it - is it an old one of yours that you found. Or did you just find one belonging to someone else.

If it belongs to someone else, give it to the police so they can try to return it. In any case you will never be able to remove activation lock.

If it is one of yours, then

https://support.apple.com/en-gb/HT201441

If the phone is already connected to her old apple id, you will be able to find the email from settings>her name

The email will be shown under her name, there.

If not, then you can still try account recovery:

https://support.apple.com/en-gb/HT204921

if you know the person who has it activation locked.. and they help you

How to remove Activation Lock - Apple Support