(original OS win7) I've installed ubuntu from wubi (so I can easily uninstall it after I try it), I've also installed some apps. I am wondering if I uninstall ubuntu, will all the files I created and apps I installed in ubuntu be removed as well or would I have to manually remove them after?
Yes - everything you did within the ubuntu-wubi installation will be removed and lost when you uninstall.
A little explanation will help.
A wubi install is in layman terms a rather large file(s) reserved within your NTFS windows 7 installation. When you uninstall wubi via the Add/Remove Program feature of Windows, you are effectively just removing this/these file(s).
Nothing in Windows itself will be removed or lost - just the Ubuntu changes.
Best advice is to backup any important files to external media such as CD/DVD or USB. Make sure you use a media format such as NTFS to allow windows to see it.
To illustrate with a diagram(sorry, few freehand circles):
All red will be destroyed. As you can see, the Ubuntu installation is inside Windows in Wubi, but not in a regular installation.