Mercurial+TortoiseHG revision back out
Here is the problem. Say, I have revision 1 and 5 (quite a lot of files and lines of code were added in the later). Now I need to return the project to the state of the 1st revision and that's what I understand the back out is for. But I always end up with all the files and lines of code I don't need anymore.
What you want is update, in your case hg update -r 1 (select revision 1 in hg workspace, right click on it and select update).
Backout has a very different meaning: it reverses the changes of one particular revision, so that afterwards it seems, that this revision did not happen (of course it is visible in the project history, but the changes to the working copy are gone.)
Files, which are not in version control can be removed with hg purge (I don't know if this command is available in tortoiseHg).
When you even don't want the revisions 2-5 anymore (and are really sure about that), you can enable the mq extension, and strip the unwanted revisions.