look in the HTML_Editor/custom foldser.
there is a seperate .js file the insert and the update page.
In each of those js files, the toolbar is defined using this code:
FCKConfig.ToolbarSets["Custom"] = [
['Source','DocProps','-','Save','NewPage','Preview','-','Templates'],
['Cut','Copy','Paste','PasteText','PasteWord','-','Print','SpellCheck'],
['Undo','Redo','-','Find','Replace','-','SelectAll','RemoveFormat'],
['Form','Checkbox','Radio','TextField','Textarea','Select','Button','ImageButton','HiddenField'],
['Image','Flash','Table','Rule','Smiley','SpecialChar','PageBreak'],
['FitWindow','-','About'],
'/',
['Bold','Italic','Underline','StrikeThrough','-','Subscript','Superscript'],
['OrderedList','UnorderedList','-','Outdent','Indent'],
['JustifyLeft','JustifyCenter','JustifyRight','JustifyFull'],
['Link','Unlink','Anchor'],
'/',
['Style','FontFormat','FontName','FontSize'],
['TextColor','BGColor']
]; /* Toolbar end */
you can re,move the names of any of the buttons you do not want to include.