If these settings are in one block, you can remove the block from the skin
./skins/default/templates/settings.html
<div class="userprefs-block">
<roundcube:object name="userprefs" form="form" parts="general,mailbox,mailview" />
</div>
<div class="userprefs-block">
<roundcube:object name="userprefs" form="form" parts="compose,folders,server" />
</div>
Just remove the parts you do not wish to use.