// Taken from the Codex
// https://codex.wordpress.org/Plugin_API/Filter_Reference/login_redirect
/**
 * Redirect user after successful login.
 *
 * @param string $redirect_to URL to redirect to.
 * @param string $request URL the user is coming from.
 * @param object $user Logged user's data.
 * @return string
 */
function my_login_redirect( $redirect_to, $request, $user ) {
    //is there a user to check?
    global $user;
    if ( isset( $user->roles ) && is_array( $user->roles ) ) {
        //check for admins
        if ( in_array( 'administrator', $user->roles ) ) {
            // redirect them to the default place
            return $redirect_to;
        } else {
            return home_url();
        }
    } else {
        return $redirect_to;
    }
}

add_filter( 'login_redirect', 'my_login_redirect', 10, 3 );


function redirect_admin(){
    if(!current_user_can('edit_posts')) {
        wp_redirect(home_url());
    exit;
    }
}
add_action('admin_init', 'redirect_admin');