There are only a couple of references in the Writings to "close" used as a verb, and both stem from Amos 9:11, which talks about closing the "breaches" in the "tent of David." In that case "close" means removing false ideas so that something can be restored. It seems likely that "close" has a similar meaning in similar uses.

(Reference: Amos 9; Arcana Coelestia 4926 [3], 10545 [7])