I have an array of arrays like this

dataSet = [['387230'], ['296163'], ['323434', '311472', '323412', '166282'], ['410119']]

I would like to delete element '311472' but do not know how. I have tried

for set in dataSet:
    for item in set:
        if item=="311472":
            dataSet.remove(item)

But this does not work

The result should be:

[['387230'], ['296163'], ['323434', '323412', '166282'], ['410119']]

Use a nested list comprehension, retaining elements instead:

dataSet = [[i for i in nested if i != '311472'] for nested in dataSet]

Demo:

>>> [[i for i in nested if i != '311472'] for nested in dataSet]
[['387230'], ['296163'], ['323434', '323412', '166282'], ['410119']]

Your mistake was to remove item from dataSet instead, but even if you removed the elements from set you'd end up with modifying the list in place while iterating over it, which means that further iteration will skip elements:

>>> lst = ['323434', '311472', '311472', '323412', '166282']
>>> for i in lst:
...     if i == '311472':
...         lst.remove(i)
...
>>> lst
['323434', '311472', '323412', '166282']

That's because the list iterator moves to the next index regardless of later additions or deletions from the list; when removing the first '311472' at index 1 the loop moves on to index 2 in a list where everything past index 1 has moved down a spot.