When I go to the Audio Edit window, selected the Drum track, selected the audio that I want to delete, got a dialog box saying "There is no RealTracks on this track. Would you like to select one?" The grammar mistake is there, too. If I select No, it does nothing. If I select Yes, it brings up the Select Best Real Tracks window.

I just edited the drums in Biab 2022(927) on an old disc with this famous Flyer, and it worked. What no longer works in the 2024 (1108).
We'll have to wait for a fix.

If you are using the BB2024 then you can do all that in the Tracks window and click on the Edit Riff button:

:

Yes I don't have the right reflexes yet, you're right.

Here's how to edit 2024 RealDrums using the Audio Edit Window.

Open the Audio Edit window, select the Drum track, select the audio you want to delete, a dialog box saying "There is no RealTracks on this track. Would you like to select one?" The grammar mistake is there too. Select Yes, it brings up the Select Best Real Tracks window. Select any RealTrack and OK to close the window and the selected region deletes.

Once a RealTrack has been assigned to the Drums Track, freeze the track or BIAB will regenerate the track but it will generate the new assigned RealTrack rather than Drums. You can continue to edit the Drums but you can't regenerate the track unless you reset the track back to the Drums style instrument.

Thanks Charlie. I've been struggling with this peculiar message for ages. I really wish that the developers would take the necessary steps to resolve this. In the meantime I'll use this workaround. Thanks again.

Yes Charlie it works, but it's really not in the manual. Great idea! I have to write it down somewhere.

You can then edit the DRUMS in all directions, it's excellent!
Just rename the track to Drums when exiting.

Useful workaround, thanks a lot. It is also very inconvenient to have this problem, to say the least. I encounter it regularly and it's super frustrating. I strongly encourage developers to fix this issue, please please please.

It's a shame you guys don't have the 2024 version as you can edit anything how you like using the Edit Riff button in the Tracks window.
The above workaround renames the drum to the chosen RT to allow deleting of a section, it's so easy to Edit any drum section using the source RealDrum file direct in Edit Riff allowing you to change a shot or push to whatever one you want without it renaming the Drum track. I can add anything back anywhere at anytime.
It works the exact same way as I showed in Reaper, allowing you to extend or change solo sections, giving total control.
I think it's well worth upgrading from your old versions to 2024 for this feature alone.

Thank you. These have been reported.