The new UI is great, and has been around for a while. Could we remove the menu entry to select the old configuration UI? Perhaps for users who still want it they can just use a setting in advanced to enable it?
Curious to ask...why does it bother you so much? I don't ever use it and have never clicked on it even seeing it dozens of times a day. I think most of the people find it easy enough to use and does what they need for what the tool is. For me, it's only the customized touch bar that matters. If there's a forced button on the touch bar to open old UI or something I don't need then sure...but I doubt this a problem that needs solving.
Try this, it should disable the menu item:
While BTT is quit run these terminal commands:
defaults write com.hegenberg.BetterTouchTool BTTDisabledLegacyUI YES
defaults write com.hegenberg.BetterTouchTool BTTNumberOfStarts 0
@ideasbegan — it doesn't personally bother me, I also ignore it 
— the point I raised is more to do with "fit and finish". As a general rule having one optimal way to do something is better for new users etc. It kind of reminds me of Windows 10 that still keeps the legacy system preferences system hanging around, although in that case it is because the new replacement is still functionally incapable of configuring windows! I only raise the question of whether there is a reason to still keep it there by default, as as far as I can see, the new UI is functionally complete and aesthetically much nicer...
@Andreas_Hegenberg — I quit BTT, then applied the two defaults commands, (also read that they are set), then restarted but the menu entry is still there.
❯ defaults write com.hegenberg.BetterTouchTool BTTDisabledLegacyUI YES
❯ defaults write com.hegenberg.BetterTouchTool BTTNumberOfStarts 0
❯ defaults read com.hegenberg.BetterTouchTool BTTNumberOfStarts
0
❯ defaults read com.hegenberg.BetterTouchTool BTTDisabledLegacyUI
YES
BTT V3.560 (1700) macOS 11.2.1