Ok to start with I'll answer the two questions posed here:
1) Can a single player delete all armies in every sector in every age that is owned by a guild?
2) if a player cannot delete all armies, what is the restriction? for example, can he delete all armies in every sector owned but on the last sector in each age he cannot delete the last army
1&2) There are no limits on the number of armies that can be deleted by any player, all armies in all ages can be deleted.
It is this that has enabled much of the HQ hopping and ghosting that is still seen. There was going to be a change to be implemented as fischh said:
The other solution of removing the delete army function and changing it to a replace army option would also prevent this sort of thing, and we were once told that would be provided in the next update but that was about 5 months ago now.
This change was mentioned in the 1.23 update:
GvG Changes and Bugfixes
The "Delete Army" option has been removed from the GvG screen
and following was
this discussion, if you read though it you may notice many posts about the issues of just removing the delete button would cause (you'll also see some posts from current moderators that were not moderators back then). There was a notification I unfortunately can't find it but in regards to the issue of "deleting armies being a workaround the release function" I found
this post.
I suspect that the "delete and replace" issue is still being worked on (unfortunately can't confirm it), many people wanted to have the ability to replace armies and understood why the delete function needed to be removed but doing only that caused other issues (can't release HQ's so there was an issue of a guild becoming stuck in an undesirable landing zone for one).
The obvious solution of providing separated gvg rights... As well I've repeatedly requested INNO create and provide gvg specific rules
I've seen no action on either of these issues, the first is still in the
ideas section, I encourage people wanting the changes in the ideas section to add their support to the threads (even if they are already popular). The more popular a thread is the better the CM/CCM's can advocate for the changes. As for the second, Inno's actions (implementing game mechanics to remove issues, even if done with varying success) show that they would rather implement fixes to the game mechanics to solve as many issues as they can rather than loading up a bunch of rules that then take up more time from the moderator team as they attempt to enforce the rules. Issues such as HQ hopping and spies deleting an empire can be fixed in game without needing rules (ghosting is a bit trickier to fix in-game but may yet be possible), rules could be made up but that distracts from the actual fixing of the problem (not to mention the extra support tickets slowing everything down).
So to sum up, we'll update you on the "delete and replace" issue when we can (it is being chased up), if you like the idea of seperate GvG rights (to help prevent spy damage and just make it a bit easier to manage rights overall) please add your support to the idea (we can advocate for it better then) and rules will not be implemented as fixes are on the way (can't confirm when or in what form sorry).