[Whai]

Ok, now I know what you want,

• Create a global array bool variable (name whatever you want like for exemple : "g_bTagHid") with the sizeof MAXPLAYERS + 1
• On "public Action Command_hidetag(int iClient, int sArgs)" remove all and write :
  
  Spoiler

  
  

  PHP Code:

  if(!iClient)
{
      ReplyToCommand(iClient, "[SM] Command only in game");
      return Plugin_Handled
}

g_bTagHidden[iClient] = !g_bTagHid[iClient] 
/* 
it's just like

if(g_bTagHid[iClient]) 
      g_bTagHidden[iClient] = false;
else 
      g_bTagHidden[iClient] = true;
*/

ReplyToCommand(iClient, "[SM] Your tag is now %s", g_bTagHidden[iClient] ? "hidden" : "showed");

return Plugin_Handled; 

• On "public Action OnClientSayCommand(int iClient, const char[] sCommand, const char[] sArgs)", just check if g_bTagHidden[iClient] is true to block the message that would display then do the "PrintToChatAll" thing