I get frustrated if I would erase all the sky tiles in one layer and create a new 'sky' layer.
I searched the document and didn't find a way to change the size of the eraser tool.
Oh... I've found a method just now. I could select and cut it using COMMAND+X - It's weird that I can't select and just delete it.
I use tiled 0.9.0 on Mac.
Yep, the method you found is the only fast way to delete larger areas right now. The eraser definitely needs to be made more efficient, so thanks for opening this issue.
One fun idea that would reuse code would be a flood-fill eraser. Maybe just hold ctrl when flood mode is on?
Another fun idea: ctrl-click a tile in the tiles palette, select all matching world map tiles that use it!
My plan for flood-fill eraser would to have a "magic wand" selection tool, though of course it could also be added under a modifier key in the eraser itself.
As for ctrl-click on a tile in the palette, that is taken because it will add the clicked tile to the stamp. @Ablu suggested to add this feature in the right-click menu in issue #7.