The Rule: Any tent which is allowed to be mantled and [thus] does not involve [the] building [prohibition], then it likewise does not involve [the] destroying [prohibition] and is [thus] permitted to be dismantled.
Removing a sheet from a bed barred with ropes: If this bed does not have placed on it leather or boards but is rather barred with ropes from above, then if there are three handbreadths between each rope, in which case we do not consider the ropes to be all attached, then it is forbidden to initially spread a sheet over it on Shabbos or place a pillow or blanket on it being that this is similar to making a tent. Similarly it is forbidden to remove the lower cloth that is on it being that this is similar to destroying a tent.
Removing the cloth covering from the barrel: The same law applies [regarding removing the cloth from the barrel] that it is forbidden to remove [a cloth] covering which covers its entire mouth if it lacks a handbreadth worth of liquid, because it is similar to destroying a tent.
Dismantling a tent which was legally mantled on Shabbos: When one adds onto a tent that was [the width of] a handbreadth from before Shabbos, it is only permitted to dismantle the material that was added [on Shabbos] however not the part of the tent that was [already] built from before Shabbos.
Whenever it is forbidden to initially set up a roofing on Shabbos then it is likewise forbidden to take it down. Thus when adding to the handbreadth of a roofing on Shabbos one may only dismantle the added material and not any of the handbreadth material which was set up from before Shabbos.
May one dismantle a roofing which was spread from before Shabbos up to a handbreadth of the roofing?
A permanent roofing: Is forbidden according to all.
 The Chazon Ish however rules that the entire roofing may be dismantled
 Avnei Nezer brought in Ketzos Hashulchan 120 footnote 17. So seems to also be the opinion of the Ketzos Hashulchan himself, [see Piskeiy Teshuvos 315 which plainly brings the Ketzos Hashulchan as following this ruling] although he brings that from the Lashon of Admur “it is only permitted to dismantle the material that was added on Shabbos” it seems that it is forbidden.
 Chazon Ish 52/7
 See footnote above in lenient opinion.