Hi Gösta,
I guess you are referring to the Classic editor (tinymce)?
There is no option, but I think it might be possible via some custom code. Try adding this code via the Code Snippets plugin or to the functions.php file in your theme/child theme directory – make sure to have a full server back-up first for safety. For more details you can check the safe coding guidelines.
remove_action('admin_head', 'wpdreams_asp_add_mce_button');
remove_action('admin_head', 'wpdreams_asp_mce_generate_variable');