Those Infamous red tiles...

[AT-AT Assault]

What are those red tiles with a black border for? They just seem to waste space(so it takes a while to scroll past them). Is there a way to delete them?

[firefly]

Those mean that there's no tile asigned in the combo, unafortunately they can't be deleted.

[Freedom]

they are empty combo slots, where you can add new combos as you build.

[LavaBall]

They are free slots for other tiles.

[MarioBrosCom]

Those are unused combo spaces. I don't see any reason to scroll past them unless they are in the middle of the the combo list, in which case you should assign them as the the combos that you'll be using.