reverse direction brushless motor with raspberry pi

I have a Raspberry PI 4. I am trying to connect my raspberry pi with two brushless motors using ESC blheli 30a. They start spinning when I run the code. Is there a way to make it spin in the reverse direction with a python script?

import time
import RPi.GPIO as GPIO
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)

GPIO.setup(7, GPIO.OUT)
GPIO.setup(11, GPIO.OUT)
t1 = GPIO.PWM(7, 50)
t2 = GPIO.PWM(11, 50)
t1.start(0)
t2.start(0)

def forward():
    print('forward')
    t1.ChangeDutyCycle(5.5)
    t2.ChangeDutyCycle(5.5)
forward()
x = input('enter: ')

if x == 's':
    t2.stop()
    t1.stop()

GPIO.cleanup()
quit()