nums = [1, 2, 3, 4]
nums.remove(3)
print(nums)

[1, 2, 4]

num = int(input("Enter number: "))

if -9 <= num <= 9:
    print("Single digit")
else:
    print("Not single digit")

Enter number:  5


Single digit

num = int(input("Enter number: "))

if -9 <= num <= 9:
    print("Single digit")
else:
    print("Not single digit")

Enter number:  9


Single digit