Often when I am selecting notes to delete my selection also includes meter markings and I hit delete and by mistake delete the metering. Is there a way to avoid this perhaps by locking or protecting metering? (see image below, this is a mistake I often make, selecting the meter with what I want to delete).
If you don’t want to select system objects, don’t select any. The easiest way to select a passage without selecting system objects is to select a note, rest or other staff-attached item at the start of the passage, release your mouse button, then Shift-click a note, rest or other staff-attached item at the end of the selection.
Marquee selections are good if you want to copy and paste or delete absolutely everything - system objects included - but are the wrong choice if you just want to clear the staff-attached stuff.