How to reverse the sequence of lighting LEDs in the Digital Hourglass project?

Using Arduino Project Guidance
1

Hello everyone!
I am very new to Arduino, and so far I am stuck on the Digital Hourglass project in the project book.
I have set up the circuit, but what I want to do when all the LEDs light up is to play a bit with the sequences, meaning keep the original timer, but turn the LEDs off from 7 to 2 with the same interval and loop it back again from the beginning. I have searched the forums and the only thing I found was to sequentially light up and turn off the LEDs, but not in the same interval as the original timer.
The code is attached. I don't know whether I should edit something in the if (led > 7) prompt or I should do something else altogether..
Please assist me and explain whether there is a typical code for such loops.

Thank you

const int switchPin = 8;
unsigned long previousTime = 0;
int switchState = 0;
int previousSwitchState = 0;
int led = 2;
long interval = 1000;
int directions = 1;


void setup() {
  // put your setup code here, to run once:
  for (int x = 2; x < 8; x++) {
    pinMode(x, OUTPUT);
  }
  pinMode(switchPin, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  unsigned long currentTime = millis();
  if (currentTime - previousTime > interval) {
    previousTime = currentTime;
    digitalWrite(led, HIGH);
    led ++;
    }
    if (led > 7){
      }
  switchState = digitalRead(switchPin);
  if (switchState != previousSwitchState) {
    for (int x = 2; x < 8; x++) {
      digitalWrite(x, LOW);
    }
    led = 2;
    previousTime = currentTime;
  }
  previousSwitchState = switchState;
}