How would I preserve only a certain user account while doing a secure wipe of my MacBook Pro? I have a MacBook Pro with a separate user account for work-related stuff.  Suppose I am required by contract to use reasonable means to destroy all copies of data that I had access to while performing the contract.

What is a reasonably secure way to wipe a single account off the machine so it's practically impossible to recover the data from that account?  Is it sufficient to simply delete the account and its contents?  (My laptop has an SSD and I presume the firmware's write optimizations make it more difficult to recover deleted data than on magnetic media.) If not, does it make any difference if I'm using FileVault?  If that still isn't secure enough, then what about deleting the account, doing a full-backup of the remaining account(s), formatting the SSD, and restoring the backup?  Presumably the backup would not include any data from the previously-deleted work account...right?  Or is there some other recommended way to selectively wipe a user account on a Mac laptop?
I would do the following: from your other admin account, delete that corporate user account in SysPrefs/Accounts.  I believe when you delete an account you have the option to leave the home folder where it is, which I would choose.

Then I would delete that account's home folder via the Terminal.app command rm -R -P /Users/TheAccountToDelete.

from man rm:

-P          Overwrite regular files before deleting them.  Files are overwritten
             three times, first with the byte pattern 0xff, then 0x00, and then
             0xff again, before they are deleted.


I am not sure if leaving FileVault on or off is the best way to accomplish this - test it out on a dummy user account first!