Is there a way to change the map size? Not the tile size, the size of the map itself.
For example, let’s say I create a map with too much space at the top, can I somehow resize or crop out the unwanted space at the top?
I’ve done a forum search but I can’t find what I’m looking for.
Map -> Resize Map… should have everything you need.
While you can use the resize function @eishiya mentioned, also note the “Crop to Selection” (which works with the current tile selection) and “Autocrop” (crops based on contents of current tile layer) actions right below, which can be more convenient.
The “Crop to Selection” also works for growing the map, when you include an area outside of your map in the selection.