After sharing your XD link with someone for review, how do you cancel their access to the file?
Thank you for reaching out and using Adobe XD. To remove access from to the shared XD link please follow below mentioned ways. If you need the published link but just you want to remove the access for others whom you have shared then you can follow below ways.
1. If you have shared a public link(Link access-Anyone with the link) then you can cancel access of shared link by changing link access to only Invited people and clicking on update link removes access for that shared public link.
2. If you have shared a private link(Link access-Only Invited people) then by removing the Invited user from shared link sharesheet and clicking on update link removes access for shared private link.
If you dont need the link and you want remove access for shared users, then you can delete the shared published link In published tab from assets web(assets.adobe.com) by clicking on manage links from links dropdown/welcomescreen or from creative cloud application.Please go through the below link to know more about end-to-end workflow on sharing:https://helpx.adobe.com/xd/user-guide.html/xd/help/share-designs-prototypes.ug.html
Please let us know if you need further assistance from us. We would be happy to help.
I would like to be able to move between public and private access, but still preserve all comments on the document. Is this possible? and if so, how do I do this?
Thank you for reaching out, and sorry for the trouble. I am afraid to say it's not possible. If it is a public XD link, then any user can access and comment on it. For the private link, the removed user's comments will still be visible to other users with access, and the user removed will no longer be able to access the link since it is private.
You may upvote this request: https://adobexd.uservoice.com/forums/353007-adobe-xd-feature-requests/suggestions/39457762-option-to... or create a new for you.
Hope it answers your question.