So you want to remove Latest Games, Newest Games, Latest Scores etc (something like the attached screenshot?)
Which arcade skin are you using - skin_Arcade.php or skin_v3arcade.php?
Either way you want to open either (or both skin files) and look for:
return <<<EOF
{$tourneyinfo['announcement']}<br />
You then want to start deleting the code that starts (it's just below {$tourneyinfo['announcement']}<br />):
<div class="tborder">
<table width='100%' border="0" cellspacing="0" cellpadding="4">
<tr>
<td align="center" width="20%" nowrap="nowrap" class="tcat"> </td>
<td align="center" width="60%" nowrap="nowrap" class="tcat">$totalstext</td>
<td align="center" width="20%" nowrap="nowrap" class="tcat"> </td>
</tr>
Right the way dow to:
</tr>
</table>
</div>
</td>
</tr>
</table>
</div>
<br />
Which is just above the start of the tournament box code:
<div class="tborder">
<table width='100%' border="0" cellspacing="1" cellpadding="4">
<tr>
<td align="center" width="100%" nowrap="nowrap" class="tcat">{$ibforums->lang['infobox_tourneytitle']}</td>
</tr>
<tr>
<td class="alt1" colspan="2">
<table width="100%" border="1" cellspacing="1" cellpadding="1">
<tr>
<td width='33%' align='center' nowrap='nowrap' class='alt1' valign='middle'>$attente<br />$actifs<br />$termine</td>
<td width='33%' align='center' nowrap='nowrap' class='alt1' valign='middle'>{$mtinfo['participe']}<br />{$mtinfo['encourse']}<br />{$mtinfo['elimine']}<br />{$mtinfo['disqualifie']}</td>
<td width='33%' align='center' nowrap='nowrap' class='alt1' valign='middle'><a href='{$ibforums->base_url}act=Arcade&do=createtourney'><b>{$ibforums->lang['create_new_t']}</b></a></td>
</tr>
</table>
</td>
</tr>
</table>
</div>
Sorry I can't give the exact code to delete, my arcade skins are different from the original but look for
return <<<EOF
{$tourneyinfo['announcement']}<br />
and you will see where the rest of the 'main content' code follows. Remember to back-up any skins before editing :)