Can I delete the Auto Save Files?

I, personally, don't delete my projects until a year after I work on them. But, if you're worried about them taking up space, deleting them won't affect your timelines or anything else.
But, not to jinx you, sometimes project files get corrupted and won't open. Something to keep in mind.

Hi -
The auto save files give you the ability to restore your project that is damaged either by a computer problem (software crash, power failure, etc.) or an editor error ( accidentally deleting a sequence, unknowingly altering a portion of the timeline, deleting a sequence and then a client changing their minds, etc.).
If you need to roll back time so that you can reset your project prior to the error, go menu File>Restore Project . . . and you will be given a choice (by the time at which the Auto Save File was made) of which Auto Save File to restore to.
The Auto Save feature is controlled by going to menu Final Cut Pro>User Preferences and looking at the General pane. There you can set how often an Auto Save Copy is made, how many copies per project are kept before the oldest are automatically deleted, and how many different projects will be kept in the Auto Save vault before the oldest is deleted.
In my case, since I am charging clients for my time, I have these values set high: I Auto Save every 2 minutes, keep 100 copies of the current project, and keep my last 25 project auto save files.
This means, should FCP crash, I will never lose more than 2 minutes of work (and you will be surprised how much work you did in 2 minutes).
So, bottom line for me, the space taken by the Auto Save files on my system disc is disc space well spent.
Hope this helps.

Message was edited by: Meg The Dog to correct typo

At the beginning of every day, I go to File > Save As and save a new project with the current day's date. I then archive the old one. This serves two purposes - it makes it easier to track changes and reduces the chances of corruption.

So I generally only make use of that day's autosaves and consequently, they are deleted after a week. I know I won't need incremental versions of last week's projects - the daily save will work for that purpose - so there's no point in me keeping autosaves from weeks or months ago.

Hi -
Yes, that is exactly what I do- the Auto Saves are basically there to cover the day, and if I need to recover a sequence form a previous day, I just open the previous days project and copy and rename the sequence and drag it into the current days project.
By Auto Saving every 2 minutes and keeping 100 copies, I am really only saving the last 200 minutes of work - about the last 3.5 hours.
I didn't want to confuse the OP by bringing in this side of the process, but you make a very good point.

Go to Final Cut Pro > System Settings and look under Autosave Vault to see the current path.

Or go to File > Restore Project.