Your collections will be visible to everyone.
They cannot be set to Logged-in users only, My pixiv only, or Private.
If you're still working on a collection, you can save it as a draft and continue editing later.
To learn more, see the FAQ below.
▼ What are collection drafts?
https://www.pixiv.help/hc/articles/49938664410009
Unpublishing a collection
To unpublish a collection, go to the bottom of the Collection settings page and select Unpublish.
Unpublished collections will only be visible to you on your own profile page.
Please note that once you unpublish a collection, you won't be able to publish it again.
Deleting a collection
To delete a published collection, go to the bottom of the Collection settings page and select Delete.
Deleted collections cannot be restored.