[Daniel100262]

So, try:

CMD:destroyallflares(playerid, params[])
{
if(!IsACop(playerid))
{
return SendClientMessage(playerid,COLOR_GREY," You cannot use this command !");
}
if(IsACop(playerid))
{
if(PlayerInfo[playerid][pRank] < 6)
{
return SendClientMessage(playerid,COLOR_GREY," Your rank is too low to be removing flares !");
}
}
else
{
if(PlayerInfo[playerid][pRank] < 5)
{
return SendClientMessage(playerid,COLOR_GREY," Your rank is too low to be removing flares !");
}
}
DeleteAllFlare();
return 1; //THIS LINE
}

should solve your problem