If your computer is alerting you that there is no space left on the disk drive when you are trying to open/save a document, you may have to free up some space on your device. There are some easy ways to fix this problem;

1. To check whether your drive has space, click Once on the Macintosh HD icon.
   
   
    
2. Press Command + I on the keyboard whilst Macintosh HD is highlighted. This window will appear. Firstly, check whether your hard drive is almost or completely full. If the available space is less than 10% of the capacity then you need to delete some files or move them to another hard drive.
   
   
    
3. If you have more than 10% of your capacity available and the message is still appearing, it may be due to the size of the item you are working on. For example, a Photoshop  or Premiere  project file is usually a large file and may take up more than 10% of the capacity. If this is the case; consider storing and running these project files on an external hard drive. This same method can be applied to other applications such as iMovie  or GarageBand .
    
4. Consider saving any other documents or project files on an External Hard Drive (USB) and restart the computer.
    
5. If the message still appears after restarting your computer then you will have to bring your computer down to 1Degree.
    

Tips for clearing disk space:

• Emptying the Trash and Restarting the Computer.
• Deleting the contents of the folders /Library/Caches and /Library/Saved Application State (follow these steps).

1. To delete the contents of /Library/Caches and /Library/Saved Application State, Click Go, then Recent Folders, then Library​. If Library does not appear from Recent Folders. Then enter ~/Library/​
   
    
2. Delete the contents of /Library/Caches and /Library/Saved Application State
   
    

• Delete un-needed items - usually the most common locations for large files will be your Downloads, Movies and Pictures folders. If you have trouble identifying what to delete, there is a program on Self Service  called GrandPerspectivethat can help you easily spot which files and folders are taking up the most space. It uses a tree map where each file is visually represented as a rectangle proportional to the amount of space it is taking up. Visit this FAQ for more information on GrandPerspective

Please checkout THIS LINKED Tutorial Video for further clarification and guidance.