nooriemad08 it won't be that simple. If you want to completely remove email and replace it with phone, you'll need to rewrite the whole login, account recovery and notification system of the backend. Also some extensions will likely stop working if the email is not present. It's doable, but if you can't develop it yourself this will probably be expensive to develop.
Just adding a phone to the registration field can be developed through an extension and should be much less work than the first option.
The only solution that might work for you without the need for custom development is the one suggested by luceos using Masquerade.
