Once the file has been added to a conversation it will stay there until it's deleted.
To delete a file, find it in the conversation's File Drawer, right-click on the file and choose Delete from the drop-down menu. This will erase the file from this conversation’s File Drawer. It will remove the file for everyone, not just yourself.
On the mobile apps, long-tap on the file to reveal the menu with Delete action.
Do note that if you are a free user of Fleep, you can only delete files you have uploaded. Fleep for Business users with admin rights can delete any files.
All deleted files and messages will be permanently deleted from Fleep servers after 14 days, in compliance with EU laws.