As @Michelist said, it’s a kind of accounting record and it’s not intended that you can decide where brushes go in the list.
You can ‘force’ the contents by selecting brushes that you’d not intend to use to that they fill the list, pushing other brushes off the bottom of the list.
Then you could select the brushes you wanted to use and they would go to the top of the list.
You can clear the list if you close krita and edit the ‘kritarc’ configuration file to delete all the entries to the right of the ‘presethistory=’ item line.
Then restart krita and you’ll have an empty history list, ready to be filled with your selected brushes.
It’s better to make and use tags to classify brush presets and they can have more that one tag so you can have tags such as ‘my favourite sketching’, ‘cool lineart brushes’, etc. that may have brush presets in common, such as an eraser.