Blender has an option to save current project as default. Then what you saved is loaded as a starting point everytime you open Blender. It also has a reset to factory option.

I've noticed I waste a lot time just removing stuff LMMS throws in at startup.

Also once it's easy to remove, maybe we could add a few drum instruments in the pattern editor like FL does - I remember it was the first thing I ever did in it. Before I knew how to load samples I could make beats! I was a child back then, bit LMMS should do it too so children if simply total newbies have easier start. The experienced users may customize their startup project anyway if we implement this.

File>Set as startup
File>Reset startup