How to delete "macOS Install Data"

Have on older Mac Pro running High Sierra 10.13.6. It had been giving me messages for weeks telling me both to upgrade to Mojave AND to run a security update to High Sierra. Been ignoring both, but did a restart, and I think I may have accidentally started an upgrade, and then accidentally aborted it. I got a message saying update couldn't be installed, and a white screen with a ton of code. Finally got out of it through the recovery drive by reselecting my startup drive rather than the installer, and computer is working fine, but I now have a folder saying "macOS Install Data" that I can't delete. Also I'm a little afraid to do another update, for fear of having the same problem.

How can I delete this folder, and is it safe to?