Example

#include <a_samp>

new gate[2];

main()
{
    print("Example.");
}

public OnGameModeInit()
{
    gate[0] = CreateObject(971, -1060.2998046875, -1338.19921875, 132.5, 0, 0, 347.99743652344);
    gate[1] = CreateObject(971, -1046.7998046875, -1334.3994140625, 132.60000610352, 0, 0, 347.99743652344);
    return 1;
}

public OnGameModeExit()
{
    return 1;
}

public OnPlayerCommandText(playerid, cmdtext[])
{
    if(strcmp("/opengate1", cmdtext, true) == 0)
    {
        MoveObject(gate[0], -1060.2998046875, -1338.19921875, 126.5, 7.5); // just decreased the 132.5 (Z value) by -6 (Change that as you like)
        /*
            Decrease the Z coordinate to make it move down.
        */
        return 1;
    }
    if(strcmp("/o1", cmdtext, true) == 0)
    {
        MoveObject(gate[1], -1046.7998046875, -1334.3994140625, 126.5, 7.5);
        return 1;
    }
    return 1;
}