Hi Veceslav, 

Welcome to the Box Community!

You can update your Box Primary email address by linking another email, and then make the new email your primary email.

Go to your Account settings > Account tab > go to "Login and Email Addresses" section and then add a new email, after successfully adding the new email, you will see a button that says "Make Primary" which gives you the option to change your default or Primary email:

Check out this article for the complete steps: https://support.box.com/hc/en-us/articles/360044196513-Manage-Account-Settings#loginandemail

Thanks for your participation in the forum!

Best,

Where do you find account settings? Everytime I try to change my email in edit profile and the verification take me to password then grey screen ??? It won't allow me to change email address now say that email is already used.