Before hiding the desired tools, you need to select them in the list. You can manually tick the check boxes next to the tools you want to hide.
You can also make use of the Check all, Check none, Check All in this group and Check none in this group context menu items to help you with the selection process, or load a previously saved selection.
Once you have selected the tools you want to hide, press Hide selected from the list, in the left pane.
Hidden tools can be restored later by pressing Restore hidden tools, in the left pane. More info here.