‘Remove Rests’ does not delete the rest, it hides it. It is meant as a tool when working with multiple voices and easily hide rests in one of the voices (it automatically applies ‘Voice ends here’ and ‘Voice starts here’ at the appropriate places).
As the rest (and corresponding beats) are not actually removed, you end up with the space in between (or so I think).
To remove the beats, you have to work with the Bars popover (Shift+B) or with the new system track in Dorico 2.
I’m not sure what you would need to type in the Bars popover for removing a number of beats.
Typing in -X removes X bars after the selection.
I do see that you have a measure-less piece, maybe it then removes a number of beats?
-Edit: or you might be able to turn on Insert mode and simply hitting Backspace. That might shift things to the left.