Disk Full. how do i delete files in recovery mode? osx wont boot. thanks

Step 1

The first step in dealing with a startup failure is to secure the data. If you want to preserve the contents of the startup drive, and you don't already have at least one current backup, you must try to back up now, before you do anything else. It may or may not be possible. If you don't care about the data that has changed since the last backup, you can skip this step.

There are several ways to back up a Mac that is unable to start. You need an external hard drive to hold the backup data.

a. Start up from the Recovery partition, or from a local Time Machine backup volume (option key at startup.) When the OS X Utilities screen appears, launch Disk Utility and follow the instructions in this support article, under “Instructions for backing up to an external hard disk via Disk Utility.” The article refers to starting up from a DVD, but the procedure in Recovery mode is the same. You don't need a DVD if you're running OS X 10.7 or later.

b. If Step 1a fails because of disk errors, and no other Mac is available, then you may be able to salvage some of your files by copying them in the Finder. If you already have an external drive with OS X installed, start up from it. Otherwise, if you have Internet access, follow the instructions on this page to prepare the external drive and install OS X on it. You'll use the Recovery installer, rather than downloading it from the App Store.

c. If you have access to a working Mac, and both it and the non-working Mac have FireWire or Thunderbolt ports, start the non-working Mac in target disk mode. Use the working Mac to copy the data to another drive. This technique won't work with USB, Ethernet, Wi-Fi, or Bluetooth.

d. If the internal drive of the non-working Mac is user-replaceable, remove it and mount it in an external enclosure or drive dock. Use another Mac to copy the data.

Step 2

You might be able to start up in safe mode even though you can't start up normally. Otherwise, start up from an external drive, or else use the technique in Step 1b, 1c, or 1d to mount the internal drive and delete some files. According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation.

Go step by step and test.

1. Start up in Safe Mode.

http://support.apple.com/kb/PH11212

This will delete some caches and will free up some space to take other steps.

2. Backup your computer.

3. Empty Trash.

http://support.apple.com/kb/PH13806

4. Disk space / Time Machine ?/ Local Snapshots

Local backups

http://support.apple.com/kb/ht4878

5. Delete old iOS Devices Backup.

iTunes > Preferences > Devices

Highlight the old Backups , press “Delete Backup” and then “OK”.

http://support.apple.com/kb/HT4946?viewlocale=en_US&locale=en_US

6. Re-index Macintosh HD.

This will take a while. Wait until it is finished.

System Preferences > Spotlight > Privacy

http://support.apple.com/kb/ht2409

7.Try OmniDiskSweeper. This will show the storage size details of the items.

https://www.omnigroup.com/more

Select Macintosh HD and click “Sweep Selected Drive” at the bottom.

Delete the files you don’t want to keep.

Be careful. Delete only the files that can be safely deleted. If you are not sure about any file, don’t touch it.

8. Move iTunes, iPhoto and iMovie media folders to an external drive.

iTunes

http://support.apple.com/en-us/HT201562

iPhoto

http://support.apple.com/kb/PH2506

iMovie

http://support.apple.com/kb/ph2289

I am attempted to recover this MBair using recovery mode. It will not load into safe mode. Disk Utility shows there to be some damage of some kind. I am attempting to use terminal in the recovery disk to mount the user's file systems to then delete their "download" folder. They claim it is full of videos that are "filling" the disk. I am in hopes that if I can manage to move to this file and dump it's contents I will then be able to boot up correctly.

So, simply put, I need to know if this is even possible. It is possible to use cd command to move to the file system on the user side. I am not the best at using command line. I found several means of listing and mounting the disks. But have been unable to actually gain access to the "Macintosh HD" file system.

Any ideas how to do this...if it is even possible