Assuming you want to remove any occurrence of 5 from the list, you should either use the "classical" erase-while-iterating pattern,

Code:
for (iter = myList.begin() ; iter != myList.end() ; )
    {
        std::cout << (*iter) << std::endl;
        if ((*iter) == 5)
            iter = myList.erase(iter);
        else
            ++iter;
    }
or use the list's member function:

Code:
myList.remove(5);