You have no idea about the structure of programming who ever made that, if you state else like 8 1/2 times, it won't be able to distinguish what it should do if its else. Here let me fix your code:
function DecollisionerProjectile::onCollision(%this,%obj,%col,%fade,%pos,%normal)
{
if(%col.getClassName() $= "fxDTSBrick")
{
if(getTrustLevel(%client,%col) == 2 || %Client.isSuperAdmin)
{
if($IsColliding[%col] == 1)
{
%col.setColliding(0);
$IsColliding[%col] = 0;
commandToClient(%client,'CenterPrint',"This brick does not have collision anymore.",3);
}
else
{
%col.setColliding(1);
$IsColliding[%col] = 1;
commandToClient(%client,'CenterPrint',"<color:33ff33>This Brick has collision now.",3);
}
}
else if(getTrustLevel(%client,%col) < 2)
{
commandToClient(%client,'centerprint',%Col.getGroup().name SPC "does not trust you enough to do that.",3);
}
}
else if(%col.getClassName() !$= "fxDTSBrick")
{
commandToClient(%client,'centerprint',"For this to work you must use it on a brick.",3);
}
}
And if that doesn't work, tell us where it syntaxes so we can actually help you, it might be wrong, I don't feel like re-reading that.