src/Traits/HasRoles.php
public function removeRole($role)
    {
        if (is_string($role)) {
            return $this->roles()->detach(Role::where('slug', $role)->first());
        }

        return $this->roles()->detach($role);
    }
public function removeRole($role)
    {
        if (is_string($role)) {
            return $this->roles()->detach(Role::where('slug', $role)->first());
        }

        return $this->roles()->detach($role);
    }
Remove a role from this user

@param string|Role $role
@return boolean