Avoid cascade erasure JPA

I have the following class:

/** 
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package modelo;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.*;

/**
*
* @author Daniel
*/
@Entity
public class Usuario implements Serializable
{
    @Id
    private String username;
    @Lob
    private byte[] fotoperfil;
    private String nombre;
    private String apellidos;
    @ManyToOne (fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private Nivel nivel;
    private String email;
    private String password;
    @ManyToMany (fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private final List<Usuario> amigos=new ArrayList();
    @ManyToMany (fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private final List<Via> viasRealizadas=new ArrayList();
    @ManyToMany (fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private final List<PeticionAmistad> peticionesAmistad=new ArrayList();

}

If I delete a User, I want to avoid cascading the relationship data. For example, if I delete a user, I want to avoid deleting the users included in the friends list.

How can you get it?