How do I get a separate image out of the tilemap? So that I can use this image anywhere I want as a sprite already

Is that the only way to do it?

This is actually pretty easy! Select your Sprite node and then add your tilemap to the texture in the inspector. Now set your "Vframes" for the vertical sprites in the tilemap and your "Hframes" for horizontal ones. The last thing you have to do is go through the normal "Frame" option in the inspector (or just type the frame value if you know it) till you find your sprite.

Boltach changed the title to Make a sprite from a tilemap .

I like the solution you posted, it's straightforward.

Another option to solve this is to open up the tile-map image in an image editor (Photoshop, Gimp, etc) and create a stand-alone sprite image. Save it separately, discard any edits to the original tile-map image, and import the new sprite image into your project.

If you're obsessive about having the smallest file sizes for your images, smaller images like this will help.