If you wish to stop sharing a file with another user, you can decide to remove any previously made share. After this operation, the old recipient of the file will no longer be able to access the contents. To remove a share:
Access the SHARED tab.
Click on the SHARED icon next to the shared file.
Click on the three-point menu next to the share you want to remove.
Click on REMOVE SHARING.
In the window that is going to appear on your screen, click on CONFIRM.