In the project bar under objects you can right click on the object you want to get rid of and click delete. I'll upload a screen shot if you aren't sure what I mean. I don't know of a way to do this for all unused object types at once, but it shouldn't be too much hassle to right click and delete each one. Hope I helped!
Yeah, but I have like 600 objects because I was testing around different sprites ect and never removed them because it was my first game, and now when I exported it, file was quite large, so I deleted some images that wasen't being used, and now the game wont load because missing files, (I tested multiple times now to readd images, delete images ect) and that is the problem!