It seems impossible to delete the barline before an open time signature?
Can you give a use case, please? I can’t envisage why you’d want to, off the top of my head.
Chant in an Evensong setting. It’s quicker to write in open metre, but I don’t want the preceding barline. I can delete any other barline.
Could we trouble you for a screenshot, with a little context? I’m still struggling, I’m afraid!
I’ve done it another way… I’ll create a simple example and post.