From Files in Account Settings, you can manage both your Shared Files and your File Tags.

Shared Files are managed by the administrator and available to every user in the account. Here you can upload presentations, price sheets, marketing collateral or anything else you might want your team to have access to. Simply click on + Add File to upload a file shared across all users. You can also delete shared files by clicking on the "Delete" icon next to the file you wish to delete. 

Click on File tags to access the File Tag portion of the Files page. Your current tags are sorted alphabetically. You can click on the pencil and paper icon to edit an existing tag or the trash can icon to delete an existing tag. Click "Add a new file tag" if you wish to add a new file tag.