How to manually unlink media?

In After Effects, it is called a "Placeholder" instead of "Offline Media".

To create a Placeholder, select the source footage in the Project tab and then choose File > Replace Footage > Placeholder.....  If needed, make changes in the New Placeholder dialog box.  The New Placeholder options default to matching the name, width and height, frame rate and duration of the source footage item that was selected.   

To relink to the source footage later, select the Placeholder and choose File > Replace Footage > File and navigate to the source footage.

I would like to see an unlink media option in After Effects, as I often have to do the same thing for clients.  I want to send them back all new media, renders, graphics, and project, but I don't want to send them the original video footage which they already have in-house.  The problem with renaming the folder with my video media is that I'm usually using that same video in a Premiere project and am multitasking when I do a Collect Files. So, it's not streamline to have to rename that folder to break the link in AE, which also breaks the link in Premiere and pauses all my work while I wait for the Collect Files process to complete.  It just seems that an unlink function in AE could be a simple fix.  Or an option in Collect Files to not collect certain file types.

I understand what you're asking.  It's time to Collect my project, which includes smaller art items I've created locally, but is linked into 50GB of the client's hi-res footage.  I want to Collect everything except that footage, and re-link the footage when I'm done collecting and organizing for delivery.

--AE 2021 will allow you to "replace with placeholder" by the same name as your footage. This allows you to temporarily disconnect it while you do a Collect on the smaller elements that you may have created locally. Multiple disconnected items will be recognized (if in the same folder) when you go to re-link.

-- Unfortunately, it does not let you "replace with placeholder" multiple items at once, so this handy method is hobbled and essentially useless to me. 

-- To solve this, I temporarily change the name of my client's hi-res source folder I'm linked into, let all the footage break, do my Collect, then repair the changed folder name.

Greg Neumayer

Antifreeze Design

If you move the file or the folder the link will be broken.

The links don’t really affect the file size so I don’t know why you would intentionally break them.