I don't think the "erase all content and settings" will work on the 2015 MacBook Pro. I believe this works only on m-series Macs, or on Intel Macs that have a t2 chip (2015 doesn't have one). I could be wrong.
IMPORTANT:
On the 2015 MBP, you need to:
- sign out of iTunes
- sign out of iCloud
- I would also go to iCloud on your NEW MB, and double-check to see that the old one "wasn't there any more".
For a quick-n-dirty "cleanup", you could do this:
1. Go to users and groups, and create a new, "temporary" account.
2. Give it administrative privileges (important step). All you need is a username and password, nothing more than that.
3. Now, LOG OUT of your "regular" account and log into the new "empty" account.
4. Next, in the new temp account, again go to users and groups.
5. Click the lock at the bottom and enter your [new temp] password.
6. Now, click on your regular account ONE TIME to select it, then click the "-" sign to delete it.
7. You will be asked if you wish to archive it or completely delete it.
8. You want to COMPLETELY delete it (make it "gone").
At this point what you do will depend on what the family member already has.
Does he/she have an older Mac?
Is it backed up?
IF it's backed up, you could connect the backup drive, then open Migration Assistant and "move stuff over".
A new account will be created on the 2015 MBP, taking the place of your old account.
Or, you could "manually create" a brand-new account for the family member. But be forewarned -- doing so could cause problems if the person THEN uses migration assistant to bring stuff over, because he/she could end up with TWO user accounts and permissions conflicts.
ASSUMING that you kept stuff "within" your home folder, all of that -- your files, data, settings, etc. -- will be gone with the deletion of the old account.
Your 3rd party installed applications will still be there, but your personal settings will be removed.
IF you kept stuff elsewhere, such as on the root level of the drive, you'll have to delete such things manually.
