My daughter has a Apple Watch. Her phone broke. She got a new phone an can’t pair her watch to the new phone because she can’t remember the password to the iCloud account. What do I do to rest her watch ?

My daughter has a watch. Her phone broke. An now she has a new phone. She can’t pair the watch to the new phone because she forgot the password to the iCloud account she used. How do I go about just resetting or finding out her email login so she can use her watch. It’s saying she had find my phone activated on her old phone also