Ok so here’s how you can remove the space.
1- Make a copy of the live theme as a backup
2- Click Action>edit code
3- search for theme.liquid file. it will be under the layout folder.
4- search for body tag and add the following code of line (check screenshot attached)
style = “margin: 0px;”
5- save the file and then refresh your website page. This should work.
If helpful then please Like and Accept as a Solution.