removing duplicate numbers from a list

[calonia]

hi, there! i am new to python and i was trying to remove duplicate numbers in a list using for loop. but the code doesn't quite work

numbers = [3, 3, 20, 6, 10, 6, 5, 5, 7, 10, 7, 19, 19, 20]
for x in numbers:
    if numbers.count(x) > 1:
        numbers.remove(x)
print(numbers)

it doesn't remove all the duplicates.

this is what i get when i run it.

Output:
[3, 6, 6, 5, 10, 7, 19, 20]