Hi texx, that’s a bit extreme! There isn’t a built-in feature to hide any of those icons, other than you can remove the Pocket icon – right-click the icon and click “Remove from Address Bar” – and access it from the Page Actions menu next to it when needed.
For everything else, you would need to create a userChrome.css file with custom style rules. You can find many recipes on the web for different modifications. In your case, you might look at the rules in this file:
https://www.userchrome.org/samples/userChrome-MaxAddress.css
It scrunches the icons together along the entire length of the toolbar, hides some parts of the site identity area, and replaces the Page Actions area with a little gray tab you can hover to slide the buttons out.
If you are using the directions on the following page, the above file would replace creating your own file, but you’ll need to rename it (remove -MaxAddress from the name):
https://www.userchrome.org/how-create-userchrome-css.html