As best I can determine, there is no way to delete individual measures and bar lines in a single system without doing the same in all systems in the score.
SCENARIO: I have a song with 8 parts. I realize that I have tied two whole notes at a point where there should only have been one whole note. I realize this after correctly writing the other instruments and the instrument in question is one bar out of sync. As it is now, whether I delete that measure or bar line in dynamic part or full score mode all instruments are affected. Then the only way to address it is to go through the entire 100+-bar piece and realign every single measure. There should be an option to make changes applicable to individual instruments/voices and not to the entire score.