If a menu bar item is still being installed after restart, then there must be an application still running to activate it.
I had a residual menu item from a trial of Go To My PC, in spite of cancelling and removing the application. Looking in the Activity Monitor window showed two processes underway that were obviously linked to G2MPC. Killing the processes removed the menu item until I restarted, but then it reappeared. Selecting each, clicking "Inspect", and then clicking "Open Files and Ports" gave me a terminal window that showed, among other things, that there was a relevant folder and files at the Macintosh HD/Library/Application Support level, although they didn't show up in Spotlight or Find FIle. Trashing those solved the problem.
I am sure you can do the same thing with Terminal, but this seems less likely to cause more problems.
P.S. For those who are new to Mac, Activity Monitor is an application in the Applications/Utilities folder. It shows the CPU use and various other processes in real time.