char ** 2dArray= NULL;
int k = 0;
int j = 0;

do{
    k++;
    for (int i= 0; i<10; i++){
        j++;
        2dArray=(char**)realloc(2dArray, (j+1)*10*sizeof(char*));
        2dArray[j-1]=(char*)malloc(10 *sizeof(char));
        ....
    }
}while(k<3)
// free the memory
for (int l = 0; l < j; l++){
                if (2dArray[l] != NULL)
                    free(2dArray[l]); // here I get the error!
                }
free(2dArray);