removing an inadvertent drop-down menu from an Excel spreadsheet.

Detlef_Lewin . The drop-down menu (see attached drop-down menu, no cell address.png) appears inadvertently, and infrequently - perhaps 4 times in the last year. I have tried deleting it, cutting it, changing the data validation to no effect. I can work around it, but it affronts me that it puts itself down where it wants, where it wants and then won't leave, spoiling the appearance of my spreadsheet! 

I use a PC with the latest version of Windows 10. I am retired so just a home user. In this instance I am using it to supplement my Indonesian language studies. I do have an excel file, an xlsm which could give a live view of the problem, but it is not accepted as a file type here.