The Clear Upload Queue button is located within the ONE desktop application's Home tab under the Overview sub-tab. The button is used to remove unwanted files and folders from the queue and can often clear up a stalled application.
Using the Clear Upload Queue button will completely clear all actions being pushed to your account that have been queued to occur. This includes things like uploads, password changes, and deletions. Choosing this button will close the ONE desktop application and re-launch it. When ONE re-launches it will begin syndication. After finishing syndication the application will open to the Home tab with your uploads Paused.
You can resume your uploads by choosing the 'Resume' button within the Overview sub-tab.