If you accidentally added some files which should have been ignored, how do you get them out of version control without losing them? Maybe you have your own IDE configuration file which is not part of the project, but which took you a long time to set up just the way you like it.
If you have not yet committed the add, then all you have to do is use TortoiseSVN → Undo Add... to undo the add. You should then add the file(s) to the ignore list so they don‘t get added again later by mistake.
If the files are already in the repository, they have to be deleted from the repository and added to the ignore list. Fortunately TortoiseSVN has a convenient shortcut for doing this. TortoiseSVN → Unversion and add to ignore list will first mark the file/folder for deletion from the repository, keeping the local copy. It also adds this item to the ignore list so that it will not be added back into Subversion again by mistake. Once this is done you just need to commit the parent folder.