How do I reduce tier donated to group, but not to 0?

In the knowledge base, I think I found the way to set to *zero* the amount of tier I've donated to a group. I do not want to do this, however, because the group still has some land it owns. I do want to *reduce* the amount of tier I've donated?

That is, suppose I have a group to which I've donated 4000sqm of tier. However, the group only owns 2000sqm of land, so I want to reclaim 2000sqm of tier for myself.

How do you do that? I haven't been able to find the answer in the knowledge base, not even in the answer to the question that seems to address it.

Thanks.

In group info, go to the land tab. You'll see the amount of tier that you donated. Just put in a new number.

Bizarre. I thought that's what it was, but before my max was low enough it suggested that that would only work for *adding* tier.

Oh well -- it must have been something slow updating from the server.

Thanks.