Error while converting from std::wstring to wchar_t*

I converted the following code containing std::wstring to wchar_t (next code block) and I am getting memory dump errors:

Below is code with std::wstring:

std::wstring RemoveFirstAndLast(std::wstring str)
{
    std::wstring removeFirst = L"";
    bool first = true;
    for (std::wstring::iterator it = str.begin(); it != str.end(); ++it)
    {
        const wchar_t *brckt = L"[";
        const wchar_t *empty = L" ";
        const wchar_t *curlyBrkt = L"{";
        if (((*it) == (*curlyBrkt)) && (first))
        {
            first = false;
            removeFirst = removeFirst + (*it);
        }
        else
        {
            removeFirst = removeFirst + (*it);
        }
    }

    std::wstring removeLast = L"";
    bool last = true;
    for (std::wstring::reverse_iterator it = removeFirst.rbegin(); it != removeFirst.rend(); ++it)
    {
        const wchar_t *brckt = L"]";
        const wchar_t *empty = L" ";
        const wchar_t *curlyBrkt = L"}";

        if (((*it) == (*curlyBrkt)) && (last))
        {
            last = false;
            removeLast = (*it) + removeLast;
        }
        else
        {
            removeLast = (*it) + removeLast;
        }
    }

    return removeLast;
}

Below is the same code as above but with wchar_t*:

wchar_t* RemoveFirstAndLast(wchar_t *str)
{
    wchar_t *removeFirst = L"";
    int length = wcslen(str);
    bool first = true;
    for (int i = 0; i < length; i++)
    {
        const wchar_t *brckt = L"[";
        const wchar_t *empty = L" ";
        const wchar_t *curlyBrkt = L"{";
        if (((str[i]) == (*curlyBrkt)) && (first))
        {
            first = false;
            wcsncat_s(removeFirst, (wcslen(removeFirst) + 1) * 2, &str[i], 1);  //removeFirst = removeFirst + (str[i]);
        }
        else
        {
            wcsncat_s(removeFirst, (wcslen(removeFirst) + 1) * 2, &str[i], 1);  //removeFirst = removeFirst + (str[i]);
        }
    }

    wchar_t *removeLast = L"";
    length = wcslen(removeFirst);
    bool last = true;
    for (int i = length; i >= 0; i--)
    {
        const wchar_t *brckt = L"]";
        const wchar_t *empty = L" ";
        const wchar_t *curlyBrkt = L"}";
        if (((removeFirst[i]) == (*curlyBrkt)) && (last))
        {
            last = false;
            wchar_t *temp2 = (wchar_t*)calloc((wcslen(removeLast) * 2) + 1, sizeof(wchar_t));
            wcsncat_s(temp2, (wcslen(temp2)) * 2, &removeFirst[i], 1);
            wcsncat_s(temp2, (wcslen(temp2)) * 2, removeLast, wcslen(removeLast));
            removeLast = temp2;
        }
        else
        {
            wchar_t *temp3 = (wchar_t*)calloc((wcslen(removeLast) * 2) + 1, sizeof(wchar_t));
            wcsncat_s(temp3, (wcslen(temp3)) * 2, &removeFirst[i], 1);
            wcsncat_s(temp3, (wcslen(temp3)) * 2, removeLast, wcslen(removeLast));
            removeLast = temp3;
            //removeLast = (removeFirst[i]) + removeLast;
        }
    }

    return removeLast;
}

The code is trying to remove first and last characters. As a beginner I was trying to understand why I am getting errors while simply converting the code from std::wstring to wchar_t*? The error creates a memory dump? Can someone please help me understand as to where am I making mistake?