public Action:OnPlayerRunCmd(client, &buttons, &impulse, Float:vel[3], Float:angles[3], &weapon)
{
     buttons &= ~IN_DUCK;
     return Plugin_Changed;
}

public Action:OnPlayerRunCmd(client, &buttons, &impulse, Float:vel[3], Float:angles[3], &weapon)
{
     if (client == индекс_твоего_игрока || GetClientTeam(client) == 3)
     {
         buttons &= ~IN_DUCK;
         return Plugin_Changed;
     }
     return Plugin_Continue;
}

// These defines are for client button presses.
#define IN_ATTACK  (1 << 0)
#define IN_JUMP   (1 << 1)
#define IN_DUCK   (1 << 2)
#define IN_FORWARD  (1 << 3)
#define IN_BACK   (1 << 4)
#define IN_USE   (1 << 5)
#define IN_CANCEL  (1 << 6)
#define IN_LEFT   (1 << 7)
#define IN_RIGHT  (1 << 8)
#define IN_MOVELEFT  (1 << 9)
#define IN_MOVERIGHT  (1 << 10)
#define IN_ATTACK2  (1 << 11)
#define IN_RUN   (1 << 12)
#define IN_RELOAD  (1 << 13)
#define IN_ALT1   (1 << 14)
#define IN_ALT2   (1 << 15)
#define IN_SCORE  (1 << 16)    // Used by client.dll for when scoreboard is held down
#define IN_SPEED  (1 << 17)    // Player is holding the speed key
#define IN_WALK   (1 << 18)    // Player holding walk key
#define IN_ZOOM   (1 << 19)    // Zoom key for HUD zoom
#define IN_WEAPON1  (1 << 20)    // weapon defines these bits
#define IN_WEAPON2  (1 << 21)    // weapon defines these bits
#define IN_BULLRUSH  (1 << 22)
#define IN_GRENADE1  (1 << 23)    // grenade 1
#define IN_GRENADE2  (1 << 24)    // grenade 2

public Action:OnPlayerRunCmd(client, &buttons, &impulse, Float:vel[3], Float:angles[3], &weapon)  
  {  
      buttons &= ~IN_DUCK;  
      return Plugin_Changed;  
  }

public Action:OnPlayerRunCmd(client, &buttons, &impulse, Float:vel[3], Float:angles[3], &weapon)    
{    
        buttons &= ~IN_USE;
        // код
        return Plugin_Continue;    
}