Change time signature without moving notes in other measures

I imported an MusicXML file from Finale, and one of the bars has this (hidden) time signature:
Screenshot 2024-09-23 at 12.54.28 PM

I assume it picked this up because one instrument (not shown here) has a different time signature (5/4) in the Finale file because it has a cadenza-like figure. I removed those notes. Now I would like to change that bar to a normal 4/4 bar without affecting the rest of the music, but when I select the red time and press delete, all the measures shown end up shifted right one beat (e.g., the e in the last measure of the second line moves to beat 2 with a rest on beat 1). Similarly if I double click on it and change the definition from 4/4,5 to just 4/4, everything gets shifted. Meanwhile if I go back to the measure where I deleted the notes, it wants to put in that fifth beat if I insert new notes (but I just want to put in 4 beats now).

How can I clear this (at least from the one instrument where it applies) without affecting the other instruments?

First thing I’d try : select the signpost and delete it (or the barline it’s attached to) without being in insert mode. Or with insert mode on, but the stop line on the barline before those notes that we see (Edit menu>Insert…>Stopline)

Thanks for that suggestion, but it didn’t work. Whether in insert mode, insert mode with Stopline, or not insert mode, the subsequent measures always get shifted when I delete the signpost.

But as I was playing around, some combination of deleting the measure altogether and adding it back did get me an empty measure in that location for which all instruments wanted only 4 beats. So somehow I ended up in a good place, though I don’t quite understand why. Fortunately, only two instruments play in that bar so putting back the music was easy enough.