what exactly are you after as a goal? The answer depends on why you'd want to do this (which has implications for what exactly this needs to be able to do).

So the order in which to do this is to
1) disable file sync in the sync tab of the preferences
2) Purge storage (which doesn't affect your local files, no)

Note that you can't "pick and choose" which files are and aren't synced within a library, so after that you will simply not be syncing any files in your personal library. You _can_ choose to still sync files for groups).

Hello, I was wondering if, once I've disabled file sync in the preferences and purge storage in my library online in order to delete all pdf files attachment that take to much space, can I re-sync in the preferences and that won't affect my local pdf attachments?
thanks for you help

Thank you very much.

To make sure I understand :

1) If I use "Purge Storage in My Library" online, I understand that it won't delete my local files (using a Mac, those who are located and saved on my hard drive here: users/namesurname/Zotero/storage/...). Is that correct?

2) Before hitting "Purge Storage in My Library" online, I have to disable file syncing in the sync tab of the preferences on my computer. Is that correct?

3) After using "Purge Storage in My Library", if I automatically or manually sync my library using the circle green arrow above the right column on my computer, with data sync ON and file sync OFF, will it delete the PDF items under each reference that allow me to access locally saved files directly from Zotero?

4) Once I'm done with purging my online library from pdf files, can I reactivate "Sync automatically" in the "Data Syncing" section in the preferences of my computer and letting the two boxes under the "File Syncing" section unchecked?

My aim is to free up storage online by deleting the PDF stored on the cloud while keeping the files saved on my hard drive on my computer AND directly accessible from my Zotero on my computer (without having to attach them manually once again after the purge). At the end of the cloud storage's purge, I'd like to have my library on my computer untouched and unmodified, i.e. with all the pdf files still saved locally AND still accessible from Zotero on my computer by a simple click.

I'm a bit worried because when I delete PDF files online manually, without using "Purge Storage in my Library", with Data sync and File sync both OFF, it deletes the PDF item on my library on my computer (maybe the PDF file also, I'm not sure). I don't want that to happen while using "Purge Storage in my Library" online or when I reactive the automatic data sync after the purge.

One last question, I'm not sure to understand the difference between "Sync full text content" and "Sync attachment files in My Library using... Zotero".

Keep full text sync on. It doesn't use storage online

Ah yes, sorry, misread the direction of 3.