char dataString[] = "Substring removing";
//cut the end: move the terminating zero
dataString[9] = '\0';
//dataString is "Substring"
printf("dataString is %s\n", dataString);
//cut the start: shift the rest left with its zero,
//memmove because the source and the target overlap
memmove(dataString, dataString + 3, strlen(dataString + 3) + 1);
//dataString is "string"
printf("dataString is %s\n", dataString);