Hello,
the toolbar has the CSS-classes "toolbar group", so you can define in userstyle.css (see
https://www.dokuwiki.org/config?s[]=userstyle.css ) that objects with this classes become hidden.
But think of negative aspects of this change, neither basic text formatting, nor wiki-links are available then (if your users don't type the code by themselves). Maybe it would be better to remove only the buttons which provide further functionality.
Have a look at inc/toolbar.php, the buttons of the toolbar are defined there.
Greetings,
Christoph