your submit button is inside the repeat region.
change:
<td colspan="2" align="right"><input type="submit" name="button_<?php echo $RepeatSelectionCounter_1; ?>" id="button_<?php echo $RepeatSelectionCounter_1; ?>" value="Löschen" /></td>
to:
<td colspan="2" align="right"><input type="submit" name="button" id="button" value="Löschen" /></td>
and move it so it is outside the repeat region.
in the future please compress the php page into a zip archive and attach the zip file to your message instead of pasting the page code.