I can't adjust a table

[Giovannino70]

I used a layout of a title page that offers me word. Which command should I use to reduce the spaces in the table, I attach image, with the red circles?

I tried to select cell> right click> table properties, option> margins, I change them but some remain as before. Maybe it depends on the size of the font?

Then it forms a circle with four points that does not erase and therefore I cannot use the delete key to reduce the space under the line?

How should I proceed?
https://i.postimg.cc/435vcXx8/Spazi.jpg
Thank you