need help with speed cut off

Trying to do a little project that has an output at 6.5kmph also 14kmph but want to try to add a feature where if the speed gets to 20kmph then enables a output and only way to disable the output will be a push button input,

sorry quite new at this, this is the sketch so far

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); ;    

#include <NMEAGPS.h>
#include <NeoSWSerial.h>
NeoSWSerial gpsSerial(6,7);  // gps on pins 6,7
NMEAGPS gps;

const int WARNING_LED_0 = 10;   // warning led on pin 10  
const int WARNING_LED_1 = 13;  // warning led on pin 13  


void setup()
{
  pinMode( WARNING_LED_0, OUTPUT );
  pinMode( WARNING_LED_1, OUTPUT );

  lcd.begin(16, 2);
  lcd.clear();
 
}

void printTime( NeoGPS::time_t & time )
{
  if (time.hours < 10)
    lcd.print( '0' );
  lcd.print( time.hours );
  if (time.minutes < 10)
    lcd.print( '0' );
  lcd.print( time.minutes );
  if (time.seconds < 10)
    lcd.print( '0' );
  lcd.print( time.seconds );

} // printTime


void displayGPS( gps_fix & fix )
{
  int kmh = 0;

  // Print speed
  lcd.setCursor(0,0);
  if (fix.valid.speed && (fix.spd.whole > 5)) {
    kmh = (fix.spd.whole * 185) / 100;
  }
  lcd.print( kmh );
  lcd.print( F(" km/h      ") );



   if (kmh > 6.5)     
    digitalWrite( WARNING_LED_0, LOW );  
  else
    digitalWrite( WARNING_LED_0, HIGH );


  

  if (kmh > 14)             
    digitalWrite( WARNING_LED_1, LOW );  
  else
    digitalWrite( WARNING_LED_1, HIGH ); 


  


  // Print time
  if (fix.valid.time) {
    printTime( fix.dateTime );
  }
} // displayGPS

void loop()
{
  while (gps.available( gpsSerial )) {  
    gps_fix fix = gps.read();           
    displayGPS( fix );                  
  }
}

So, light the next LED when the speed is over 20. But don't turn it off there. After a digitalWrite() the pin will stay at whatever level you set it until you set it to something different.

Then elsewhere in the code where you're reading buttons and deciding what to do with them (not inside the GPS display function, that should not be reading buttons when its name is 'display') you could read the button and turn that LED off when pushed.

thank you