SharePoint - How to manage access in a web browser
As an administrator or owner of a library, you can change permissions to let the right people access the data they need while restricting others.
Sign in to SharePoint, then go to the file or folder
Click the Information in the upper right corner to open the details pane.
Click the Information in the upper right corner to open the details pane.
Click Manage Access to view the list.
Click on Grant Access to add or remove a participant.