As far as I’m aware there’s no situation where frame breaks are created automatically, except where the “make into frame” button has been clicked.
Given there’s a frame break at the top of the previous page, I suspect that you DID use the “make into frame” button, but you made fell into the trap of selecting the first and last NOTES you wanted on the page. You need to select the first note and the last barline you want on the frame (page) OR the first note you want on that page and the first note you want on the NEXT page. Though this may seem counterintuive, I believe it’s because breaks are entered at the rhythmic position at which the note begins (e.g. the start of the note).
Regardless, they’ve very easy to delete. Select the purple “Frame Break” signpost and hit the delete or backspace key on your keyboard.