Dynamic Memory issue in C++

so I was writing a program which has to check if the input sting is a palindrome or not. And it's actually working but a problem with deleting the array I created during the course of it arouse.

#include <iostream>

using namespace std;

bool checkPalindrome(char* text);
char* clearString(char* src);


int main() 
{
    char buffer[1000];
    cin.getline(buffer, 1000);

    cout << boolalpha << checkPalindrome(buffer) << endl;

    return 0;
}


bool checkPalindrome(char* text)
{
    char* newStr = clearString(text);
    if (!newStr)
       return false;

    int newLen = strlen(newStr);

    for (int i = 0; i < newLen / 2; i++) {
        if (newStr[i] == newStr[newLen - i - 1])
            continue;
        else
            return false;
    }

    //delete[] newStr;

    return true;
}


char* clearString(char* src)
{
    unsigned len = strlen(src);
    unsigned counter = 0;

    for (int i = 0; i < len; i++) {
        if (src[i] == ' '||src[i] == '.'||src[i] == ','||src[i] == '!')
            counter++;
    }

    unsigned newSize = len - counter + 1;
    char* dest = new(nothrow) char[newSize];

    if (!dest) {
        cout << "not enoough memory\n";
        return NULL;
    }

    int i, j;

    for(i = j = 0; j < newSize; ++i, ++j) {
        if(src[i]==' '||src[i]=='.'||src[i]==','||src[i]=='!'||src[i]=='?')
            i++;
        else
            dest[j] = src[i];
    }

    dest[j] = '\0';

    return dest;
}

So the commentated delete in the checkPalindrome function causes a crash if executed and I get the "Heap corruption detected" error. I tried changing the function type to void and delete there and the same thing happened. Any ideas what causes it?