This is NOT SOLVED.  This has been happening since the QB 2016 version.

I use the top icon bar in the desktop program. (Currently QB 19 Accountant) I click customize and uncheck search bar. It goes away. Every time I reopen quickbooks it shows up again! It is covering up my icon buttons I DO use. I can't believe you haven't fixed this. Everyone is complaining online.  It may seem like a small thing, but I open quickbooks every day and EVERY DAY I have to turn off the stupid search box.