Anyone can tell me how I can remove/edit the components of these shapes in the background? I can’t seem to touch them with my mouse, they seem locked? I attached a screenshot for reference.
I’d guess that there are no paths in the foreground layer of the B glyph, but only paths in the background layer which are being shown with View > Show Background enabled. That shaded B placeholder will disappear once you start drawing in the B glyph.
When there are no shapes (paths, components, …) in a glyph, Glyphs will show a grey placeholder representing that glyph so it’s easy to quickly see which glyph you’ll be drawing in. As soon as you start drawing, the placeholder will disappear.
If you’re asking how paths ends up in the background layer, there are multiple ways: Path > Selection to Background (Command-J) to copy the selected paths to the background layer, Path > Swap with Background (Control-Command-J) to swap the foreground and background layers, Edit Background (Command-B) to toggle editing of the background later and drawing paths there.