Updating Mac OS from Mavericks to Catalina

Answer : if you're being asked to create a new ID then no, you shouldn't erase it. Normally, when reinstalling an OS for a new user, you'd quit the installer at the point where it's installed and asking for user details, so the new owner can do that bit.

In your case, I'd create a new user with just the basic stuff in, and an easy password to give the new owner. They can then set up a new admin user with their own details, then erase the user you created. That would be the simplest way to proceed.

The official Apple line is that when preparing a mac for reselling the it should be prepared with its original

operating system.

What to do before you sell, give away or trade in your Mac – Apple Support

Although in theory you can upgrade directly from Mavericks to Catalina it has proven problematic

as the install stalls as it tries to convert the drive from HFS+ to APFS. One way to get a round that

is to upgrade to High Sierra first. You could try that and see if you can upgrade without using your

AppleID, although that could be problematic as you will need to set up High Sierra before you can

upgrade to Catalina. If you can do that and go through the upgrade to Catalina then remember to

leave the Catalina upgrade at the set up stage so the new owner can apply their AppleID to the mac.

Use Safari to click on this link, do not use Firefox.

How to upgrade to macOS High Sierra - Apple Support