If the location of the backup is starting to run out of space, you can use the backup client to remove obsolete files. This will increase the space available and prevent any issues that may arise if the space were to become to low.
Here is how you perform this task.
Firstly, open up the backup client. Once open, please click the 'Utilities' button
Once the Utilities tab is open, choose Space Freeing Up from the list on the left.
You can now select the backup set you need, as well as the location that you wish to clear space from.