I have searched this site for an answer but can't find one.

I create an XL file with one worksheet and then I copy the sheet (using
'Copy or Move sheet') to another XL file. In addition to copying the
sheet to my other workbook, this creates another file that is '.htm'
So now I have one file that is '.xls' with multiple sheets and another
file that is '.htm' for each sheet that I have copied and moved. How
do I avoid the .htm creation - because when I delete the .htm, that
sheet in my .xls file disappears.

I have looked at Edit/Links but this is grayed out for all sheets.