Highlighted text can't be cut due to entire cell selected.
Cause:
The entire cell is probably selected, NOT just the text.
Solution:
Select the TEXT ONLY and then delete it.
1) Select the TEXT ONLY by doing the following:
a) Click in the cell.
b) Drag the mouse over the TEXT ONLY. (The text is highlighted.)
Only text selected
Entire cell selected
NOTE: The entire cell can be accidentally selected when clicking in the cell but not on any text (that is, clicking in the blank part of the cell). Make sure to highlight only the text, not the entire cell.
2) Select the 'Edit' menu and select 'Delete' or 'Cut'. (The text is deleted, but the cell is not.)