I may be completely wrong on this but I have played it that an element is only giving rear support if the element in front is actually in combat. If the front element is not in combat, they are just two elements in column and so can choose to break up the group if they wish.
I think the scenario suggests that the element in front is in combat, otherwise the question doesn't make sense.
A distinction is made if a flank contact is intended with an element which is providing rear support (war band, pike) and therefore cannot be contacted individually and forced to turn (when the contact has to be with the front corner of the front element), and one which is simply in column, which can be contacted individually and forced to turn and thus deny the front element recoil.
I would suggest that this distinction therefore also operates when considering whether retiring is possible.
I suggest the answer to the question is yes, it is in close combat, and therefore cannot retire.
Yes the front Warband element was in close combat but had lost its flank guard due to following up a recoil.The Warband was now out flanked on both sides and next move would see the gate closed causing the loss of two elements. The option to retire the Rear Support Element looked a wise move at the time. Thanks for your replies.
The rules define stands as being in close combat, in overlap and providing rear support.
The movement section only states that in close combat can not break-off (quoted from an early play test version):
"A tactical move by a single element can be in any direction, even diagonal or oblique, can pass through any gap its leading (not necessarily its front) edge can fit through and can end facing in any direction. It cannot be used by an element in close combat, which can break-off only by a recoil or flee outcome move."
I can find nothing to stop an element providing rear support from moving to it's own rear.
I think we have a problem with the language here. If an element is going to close the gate then it cannot be flanking the enemy as closing the gate ends up with a flank contact. Do you mean that there were two elements overlapping the one in combat? And the next move those elements could go from overlapping to flanking?
When you say "retire " do you really mean "break off " from combat. In previous editions an element in contact could break off, and back up. In the new rules this is not allowed.
So the question is, can a supporting elements back up from the supporting position. It is probably in the threats zone of the enemy element in front, so has TZ restrictions.
Supporting an element in close combat is not close combat. Note the rule on shooting that differentiates between close combat and support.
"Shooting is not possible if either shooters or target are in close combat or providing rear support, ..."
Only the elements in close combat cannot break off.
" It cannot be used by an element in close combat, which can break-off only by a recoil or flee outcome move." "It "refers to a tactical move.
On re reading the rules with my glasses on I 'see' "Close Combat occurs when an element moves into, or remains in, both front edge and front corner-to-corner contact with an enemy element...." Elements giving rear support therefore do not qualify for the definition of 'close combat' so can retire as per the TZ rules.