In almost in all Files you you are able to add documents at the "Attachments-tab".
Remove an attachment
Open a file
Open a record
Go to "Atachment-tab"
Select the attachment(s)
Click [Action] button, choose [Delete]
Checkbox for selection is not visible
At the Attachments-tab in a file you see several files.
However, the checkbox to check this document(s) is missing and so your are not able to remove (some of these) attachments.
Reason
The Attachments without checkbox does not belong to the file itself, but to a related file. You are only able to remove an Attachment in the file where it directly belongs to.
In general:
Source... : Also visible at
Candidate: Match
Job order: Match
Contact: Match, job order
Company: Match, Job order file, Contact
User: All the files where the user is the Owner
Office: All the files where the Owner belongs to the Office
Tip: Add directions to the Office so the directions are always available.